Transcript: PHY 21041 Lab 8
Hi again! Well back in Lab 4, you measured the speed of sound in two different ways.
That’s quite an accomplishment because sound travels as fast as a bullet or a jet plane.
In this lab, your mission‐ should you decide to accept it‐ is to measure the speed of light!
Light‐ about a million times faster than sound. And it may sound crazy, but one way to
do that‐to measure the speed of light‐ is to use a microwave safe plate, and uh,
marshmallows, or chocolate chips, or a candy car. This one fell over. I’ll just eat.
Okay, not the speed of light, exactly, but of microwaves, a cousin of light. Use an
ordinary microwave oven, take out the tray inside and the roller mechanism, so it won’t
rotate, put the plate of marshmallows or chocolate inside, set it for about thirty seconds
or so and let it run. What you’ll see when you take the plate out, is little melted spots in
the marshmallows or chocolate. They correspond to the locations of the antinode of
the standing wave inside the oven. You want to measure the distance in centimeters
between those hot spots as accurately as you can, then follow the directions in Learn.
And believe it or not, you’ll be able to calculate the speed of microwaves, and the speed
of light! You’ll also see from this of course, why it is that microwave ovens have those
turntables to move the food through those antinode hot spots to heat it more evenly.
We have a more high‐tech way to measure the speed of light directly, as well, with this
equipment. On the left we have a precision, high speed oscilloscope. In the center; a
speed of light module kit; on the right side, a spool of 20 meters of fiber optic cable‐ it
looks like wire, but it’s actually plastic fiber. Here we have a little light emitting diode
that gives off very brief, very rapid pulses of light. If you looked inside the hole, here,
you’d see a steady red light because it happens too fast for us to see.
The light travels out of here, around and around and around this fiber optic cable‐ 20
meters of cable, a little more than 60 feet of cable, comes back in here, where if you
see, by a photo transistor. All this circuitry just runs these two devices here. These
wires bring the signals over to the oscilloscope.
On the oscilloscope, the top track shows the pulse as being sent out, and the bottom
track or graph shows the pulse being received. There will be a picture of this in the
instructions on Learn, and from that you’ll be able to measure the time delay between
here and here. That’s the time it took for light to travel 20 meters. It’s amazing we can
measure something as fast as light going in such a short distance as 20 meters, just
amazing!
macaulay.cuny.edu
Kent State University
Act IIILab 8 Lab 8
Measuring the speed of light
The idea: Part 1 of this lab is short and sweet – literally! Part 2 is not bad either.
There is something special about the speed of ligh ...
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
The speed of light is one of the most important topics in physics. It is so important because it tells us so much about our universe. The speed of light is the maximum speed at which any particle can travel, it’s the ultimate speed limit. The funny part is that we don’t know why it is so.
This speed limits prohibits time travel and prevents us from going back in time like doctor who. In this paper I discuss different cases where the speed limit is thought to broken, why it makes meeting my ‘brother from another plant’ improbable and what happens when we try to break such rules in physics. I also discuss the very interesting theories of relativity and why light is special, it does not accelerate. So as soon as you light a match stick the light moves at the speed of light it doesn’t take time to acquire that speed.
Chapter 1924. If you dip your finger repeatedly into a puddle of.docxcravennichole326
Chapter 19
24. If you dip your finger repeatedly into a puddle of water, it creates waves. What happens to the wavelength if you dip your finger more frequently?
Chapter 20
29. What two physics mistakes occur in a science fiction movie that shows a distant explosion in outer space, where you see and hear the explosion at the same time?
Chapter 21
26. Tom Senior makes music by setting small columns of air into vibration by blowing across the ends of drinking straws of various lengths. Which straws, the short ones or the long ones, produce lower pitch? What would you expect of the pitch produced by the much larger musical instrument behind Tom that uses resonant air columns excited by striking the ends of the tubes with paddles?
Chapter 26
5. Which has the shorter wavelengths, ultraviolet or infrared? Which has the higher frequencies?
Chapter 27
17. On a TV screen, red, green, and blue spots of fluorescent materials are illuminated at a variety of relative intensities to produce a full spectrum of colors. What dots are activated to produce yellow? Magenta? White?
Chapter 28
7. Why is the lettering on the front of some vehicles “backward”?
Chapter 29
3. Why do radio waves diffract around buildings, while light waves do not?
Chapter 30
4. Ultraviolet light causes sunburns, whereas visible light, even of greater intensity, does not. Why is this so?
32. Cite at least two reasons for predicting that LEDs will emerge as more popular than CFLs.
Name
Date
Class
Lab 28: Diffraction and Interference
Purpose
To study single slit diffraction and double slit interference patterns
Background
It has long been known that if you shine light through narrow slits that are spaced at small intervals, the light will form a diffraction pattern. A diffraction pattern is a series of light and dark areas caused by wave interference. The
wave interference can be either constructive (light areas) or destructive (dark areas). In this experiment, you will shine a laser through a device with two slits where the spacing can be adjusted and investigate the patterns that are
produced on the far side of the slits.
Skills Focus
Predicting, drawing conclusions, observing, interpreting data, making generalizations, applying concepts
Procedure
1. Start Virtual Physics and select Diffraction and Interference from the list of assignments. The lab will open in the Quantum laboratory.
2. A laser is used as the light source in this experiment because it has a single wavelength. Therefore, you will not see diffraction patterns from other wavelengths interfering in the image. What is the wavelength of the laser?
What is the spacing of the two slits on the two slit device? This is the gap
between the two different slits. How do the wavelength of the laser and the spacing of the slits compare?
3. Predicting
How will the diffraction pattern change as the wavelength is
made smaller and the slit spacing remains the same? Hint: Think about the spacing as an obstacle that ...
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
The speed of light is one of the most important topics in physics. It is so important because it tells us so much about our universe. The speed of light is the maximum speed at which any particle can travel, it’s the ultimate speed limit. The funny part is that we don’t know why it is so.
This speed limits prohibits time travel and prevents us from going back in time like doctor who. In this paper I discuss different cases where the speed limit is thought to broken, why it makes meeting my ‘brother from another plant’ improbable and what happens when we try to break such rules in physics. I also discuss the very interesting theories of relativity and why light is special, it does not accelerate. So as soon as you light a match stick the light moves at the speed of light it doesn’t take time to acquire that speed.
Chapter 1924. If you dip your finger repeatedly into a puddle of.docxcravennichole326
Chapter 19
24. If you dip your finger repeatedly into a puddle of water, it creates waves. What happens to the wavelength if you dip your finger more frequently?
Chapter 20
29. What two physics mistakes occur in a science fiction movie that shows a distant explosion in outer space, where you see and hear the explosion at the same time?
Chapter 21
26. Tom Senior makes music by setting small columns of air into vibration by blowing across the ends of drinking straws of various lengths. Which straws, the short ones or the long ones, produce lower pitch? What would you expect of the pitch produced by the much larger musical instrument behind Tom that uses resonant air columns excited by striking the ends of the tubes with paddles?
Chapter 26
5. Which has the shorter wavelengths, ultraviolet or infrared? Which has the higher frequencies?
Chapter 27
17. On a TV screen, red, green, and blue spots of fluorescent materials are illuminated at a variety of relative intensities to produce a full spectrum of colors. What dots are activated to produce yellow? Magenta? White?
Chapter 28
7. Why is the lettering on the front of some vehicles “backward”?
Chapter 29
3. Why do radio waves diffract around buildings, while light waves do not?
Chapter 30
4. Ultraviolet light causes sunburns, whereas visible light, even of greater intensity, does not. Why is this so?
32. Cite at least two reasons for predicting that LEDs will emerge as more popular than CFLs.
Name
Date
Class
Lab 28: Diffraction and Interference
Purpose
To study single slit diffraction and double slit interference patterns
Background
It has long been known that if you shine light through narrow slits that are spaced at small intervals, the light will form a diffraction pattern. A diffraction pattern is a series of light and dark areas caused by wave interference. The
wave interference can be either constructive (light areas) or destructive (dark areas). In this experiment, you will shine a laser through a device with two slits where the spacing can be adjusted and investigate the patterns that are
produced on the far side of the slits.
Skills Focus
Predicting, drawing conclusions, observing, interpreting data, making generalizations, applying concepts
Procedure
1. Start Virtual Physics and select Diffraction and Interference from the list of assignments. The lab will open in the Quantum laboratory.
2. A laser is used as the light source in this experiment because it has a single wavelength. Therefore, you will not see diffraction patterns from other wavelengths interfering in the image. What is the wavelength of the laser?
What is the spacing of the two slits on the two slit device? This is the gap
between the two different slits. How do the wavelength of the laser and the spacing of the slits compare?
3. Predicting
How will the diffraction pattern change as the wavelength is
made smaller and the slit spacing remains the same? Hint: Think about the spacing as an obstacle that ...
Bio 102 – City College of New York – Biology Dept.Experiment 2ChantellPantoja184
Bio 102 – City College of New York – Biology Dept.
Experiment 2: Conduction Velocity – How fast is a neuron?
Purpose:
We will study Conduction velocity—measuring the speed at which an action potential propagates down the medial neuron.
Objectives
After this exercise you should be able to:
1. learn how to measure the conduction velocity of neural action potentials using an earthworm preparation.
2. get an introduction to a basic electrophysiology laboratory setup using simple amplifiers and laptop computers to amplify and record neural data.
3. gain general process knowledge such as how to observe, collect, and analyze physiology data.
4. learn statistical hypothesis testing between two populations of data, and novel experiment design
Materials:
· Lumbricus terristrius
· 10% ethanol solution
· 2-channel SpikerBox
· Faraday Cage
· a piece of balsawood or thick cork
· USB cable
· Laptop with Spike Recorder software
· Ruler
· Tape
· Marker
Background
You probably think the nervous system is pretty fast. You seem to hear the spikes immediately when you touch the leg of the cockroach or blow on the cerci of the crickets. But is it instantaneous? Of course not! Not even light, the fastest signal in the universe, travels instantaneously. But how fast is a nervous system? Is it faster than a car, faster than a jetplane, or faster than a cell phone? And how can we measure it?
To measure speed (velocity) though, you need to measure both time (when a spike occurred) and distance (how far a spike has travelled down a nerve).
Take the analogy of a car on a highway. If you were looking out of a small observation hut by the road, you could tell what whether you saw a car, what kind of car it was, and the time that you saw it.
Similarly with your SpikerBox, you can currently tell if you saw a spike, perhaps what kind of neuron generated that spike (we will discuss this in a later experiment), and the time you saw the spike, but you can’t tell how fast the spike was travelling down the nerve.
Let’s go back to the car on the highway. Suppose you had a friend ½ mile down the road in a similar hut:
Later, you two could compare notes to determine the speed of the car. 1 minute = 0.016 hours. Dividing ½ mile by 0.016 hours = 31.25 mph.
[illustration]
So, why don’t we take our two-channel SpikerBox with our two electrodes and ground, put it in the cockroach, and measure the spike output of the two channels? You will notice immediately that there are a lot of spikes happening, in fact, way too many to keep track of it all.
Let’s go back to our analog of the road. Imagine a very busy, fast moving street with many similar looking cars, say, Lakeshore Drive in Chicago, and you and your friend can only set up stations very close to each other.
Ideally, given our limited tools, we’d want to measure spikes on a longer nerve, a nerve with only 1-3 large axons in it, and axons that do not fire many spikes.
Is there any creature in the animal king ...
The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. In this paper a new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone! This is done by use of microwaves.
Exam #3 ReviewChapter 10· Balance of payment statements · .docxturveycharlyn
Exam #3 Review:
Chapter 10:
· Balance of payment statements
· Know all the components of the balance of payment statements
· Balance of international indebtedness
· Know the debit and credit transactions of the balance of payments.
· Which is debit and which one is credit
· What determine the US balance of trade
· Essay: How do we measure international investment position of the US?
· Essay: How did the US become the net debtor so quickly?
Chapter 11:
· What happened to the international merchandise transactions (trade) if the US dollar is appreciated or depreciated against other currencies?
· What depreciation is and what appreciation is?
· Know the differences between the spot market and the forward market?
· What is spot market
· What is forward market
· How do you prevent the loss and remove the risks of a foreign currency transaction?
· Essay: How do you trade on the future market?
· Essay: Differences of trading between in the future market and the forward market?
Chapter 15:
· Study Manage floating exchange rate system.
· What happens to the US dollar if the inflation of the US and inflation in a foreign country are different?
· Which exchange rate system does not require monetary reserves?
· Under the floating exchange rate system, if import and exports increase or falls, what happens to the dollar value?
· What happens to the balance of trade when the currency is appreciated or depreciated?
· Essay: difference between current pect and adjustable pect exchange rate.
Bonus question about the video that wi will finished on monday.
ECO-358: Assignment 4, Article Analysis
1. Please read the attached article several times and highlight its main points and/or arguments. If you need additional research to write your analysis of this article, please do so and cite your sources appropriately and make up a reference page at the end of your assignment to list sources (APA format is required).
2. Choose 7 concepts and/or theories from our textbook to use as guidance and foundation to analyze the article. These concepts and theories can be from any chapter of the textbook. You should choose concepts and theories that are broad/big/important enough so you can write a lot about them with information from the article. Simple definitions don’t have much to write, don’t choose them.
3. Your paper must include an article summary (very short one, just 1 paragraph), a body, and a brief conclusion. Please show me how the article contents relate to the concepts/theories you choose or vice versa. Each concept/theory has to be underlined and also has textbook page number reference on your paper. The minimum length is 5 double space pages, excluding title and reference pages.
4. Your paper has to be in APA format and style. Visit Doane College writing center, or read APA guide posted on BB for guidance on APA writing. There are many requirements on APA format. Here are some most basic and essential ones you must have on your paper: cover page,.
Bio 102 – City College of New York – Biology Dept.Experiment 2ChantellPantoja184
Bio 102 – City College of New York – Biology Dept.
Experiment 2: Conduction Velocity – How fast is a neuron?
Purpose:
We will study Conduction velocity—measuring the speed at which an action potential propagates down the medial neuron.
Objectives
After this exercise you should be able to:
1. learn how to measure the conduction velocity of neural action potentials using an earthworm preparation.
2. get an introduction to a basic electrophysiology laboratory setup using simple amplifiers and laptop computers to amplify and record neural data.
3. gain general process knowledge such as how to observe, collect, and analyze physiology data.
4. learn statistical hypothesis testing between two populations of data, and novel experiment design
Materials:
· Lumbricus terristrius
· 10% ethanol solution
· 2-channel SpikerBox
· Faraday Cage
· a piece of balsawood or thick cork
· USB cable
· Laptop with Spike Recorder software
· Ruler
· Tape
· Marker
Background
You probably think the nervous system is pretty fast. You seem to hear the spikes immediately when you touch the leg of the cockroach or blow on the cerci of the crickets. But is it instantaneous? Of course not! Not even light, the fastest signal in the universe, travels instantaneously. But how fast is a nervous system? Is it faster than a car, faster than a jetplane, or faster than a cell phone? And how can we measure it?
To measure speed (velocity) though, you need to measure both time (when a spike occurred) and distance (how far a spike has travelled down a nerve).
Take the analogy of a car on a highway. If you were looking out of a small observation hut by the road, you could tell what whether you saw a car, what kind of car it was, and the time that you saw it.
Similarly with your SpikerBox, you can currently tell if you saw a spike, perhaps what kind of neuron generated that spike (we will discuss this in a later experiment), and the time you saw the spike, but you can’t tell how fast the spike was travelling down the nerve.
Let’s go back to the car on the highway. Suppose you had a friend ½ mile down the road in a similar hut:
Later, you two could compare notes to determine the speed of the car. 1 minute = 0.016 hours. Dividing ½ mile by 0.016 hours = 31.25 mph.
[illustration]
So, why don’t we take our two-channel SpikerBox with our two electrodes and ground, put it in the cockroach, and measure the spike output of the two channels? You will notice immediately that there are a lot of spikes happening, in fact, way too many to keep track of it all.
Let’s go back to our analog of the road. Imagine a very busy, fast moving street with many similar looking cars, say, Lakeshore Drive in Chicago, and you and your friend can only set up stations very close to each other.
Ideally, given our limited tools, we’d want to measure spikes on a longer nerve, a nerve with only 1-3 large axons in it, and axons that do not fire many spikes.
Is there any creature in the animal king ...
The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. In this paper a new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone! This is done by use of microwaves.
Exam #3 ReviewChapter 10· Balance of payment statements · .docxturveycharlyn
Exam #3 Review:
Chapter 10:
· Balance of payment statements
· Know all the components of the balance of payment statements
· Balance of international indebtedness
· Know the debit and credit transactions of the balance of payments.
· Which is debit and which one is credit
· What determine the US balance of trade
· Essay: How do we measure international investment position of the US?
· Essay: How did the US become the net debtor so quickly?
Chapter 11:
· What happened to the international merchandise transactions (trade) if the US dollar is appreciated or depreciated against other currencies?
· What depreciation is and what appreciation is?
· Know the differences between the spot market and the forward market?
· What is spot market
· What is forward market
· How do you prevent the loss and remove the risks of a foreign currency transaction?
· Essay: How do you trade on the future market?
· Essay: Differences of trading between in the future market and the forward market?
Chapter 15:
· Study Manage floating exchange rate system.
· What happens to the US dollar if the inflation of the US and inflation in a foreign country are different?
· Which exchange rate system does not require monetary reserves?
· Under the floating exchange rate system, if import and exports increase or falls, what happens to the dollar value?
· What happens to the balance of trade when the currency is appreciated or depreciated?
· Essay: difference between current pect and adjustable pect exchange rate.
Bonus question about the video that wi will finished on monday.
ECO-358: Assignment 4, Article Analysis
1. Please read the attached article several times and highlight its main points and/or arguments. If you need additional research to write your analysis of this article, please do so and cite your sources appropriately and make up a reference page at the end of your assignment to list sources (APA format is required).
2. Choose 7 concepts and/or theories from our textbook to use as guidance and foundation to analyze the article. These concepts and theories can be from any chapter of the textbook. You should choose concepts and theories that are broad/big/important enough so you can write a lot about them with information from the article. Simple definitions don’t have much to write, don’t choose them.
3. Your paper must include an article summary (very short one, just 1 paragraph), a body, and a brief conclusion. Please show me how the article contents relate to the concepts/theories you choose or vice versa. Each concept/theory has to be underlined and also has textbook page number reference on your paper. The minimum length is 5 double space pages, excluding title and reference pages.
4. Your paper has to be in APA format and style. Visit Doane College writing center, or read APA guide posted on BB for guidance on APA writing. There are many requirements on APA format. Here are some most basic and essential ones you must have on your paper: cover page,.
eworkMarket45135.0 (441)adminNew bid from Madam Cathy.docxturveycharlyn
ework
Market
45
13
5.0
(441)
admin
New bid from Madam Cathy
here is my bid
admin
TJ2021 accepted the bid and paid the down payment
Im about to post the second one
okay dear
Do you know how to do power point videos
the powerpoint document or videos?
Let me see. One min
okaydear
Prior to beginning work on this video presentation, read Fourth Amendment: Search and Seizure (Links to an external site.), The Difference Between the 5th and 6th Amendment Right to Counsel (Links to an external site.), Probable Cause and Reasonable Suspicion (Links to an external site.), Saul Ornelas and Ismael Ornelas Ledesma, Petitioners v. United States (Links to an external site.), and Pre-Trial Motions (Links to an external site.). The fourth, fifth and sixth amendments are the most important of the Bill of Rights which affect criminal law, prosecutions, and defenses in the United States. Consider the protections against unreasonable searches and seizures, the right to remain silent, the right to due process, the right to counsel, and the right to a speedy trial as the “Holy Grail” of constitutional protections for those accused of a crime. Part 1: Your PowerPoint (or equivalent) presentation: If your last name begins with the letters A through G (fourth amendment). Create a five- to eight-slide PowerPoint explaining the fourth amendment. Additionally, provide 50 to 75 words of explanations for each of your PowerPoint slides in the discussion area, just as you would present an oral presentation explaining the slides on the topics listed. In your PowerPoint slides and discussions, List the requirements of the fourth amendment. Define the key term warrant, and provide exceptions to the warrant requirement. Examine what the remedy is for a defendant when a motion granted to suppress is granted for a fourth amendment violation. In all presentations, support your observations using a minimum of two scholarly and/or credible sources either from the required readings this week or from independent research that you conduct in the University of Arizona Global Campus Library or online, and properly cite any references. Making your PowerPoint (or equivalent) Presentation You may wish to include visual enhancements in your presentation. These may include appropriate images, a consistent font, appropriate animations, and transitions from content piece-to-content piece and slide-to-slide. (Images should be cited in APA format as outlined by the University of Arizona Global Campus Writing Center’s Tables, Images, & Appendices (Links to an external site.) resource.) The Where to Get Free (and Legal) Images (Links to an external site.) guide provides assistance with accessing freely available public domain and/or Creative Commons licensed images. It is recommended that you access the University of Arizona Global Campus Writing Center’s How to Make a PowerPoint Presentation (Links to an external site.) and Simple Rules for Better PowerPoint Presentations (Links to an external site.
Evolving Technology Please respond to the following Analyze t.docxturveycharlyn
"Evolving Technology"
Please respond to the following:
Analyze the various technological improvements over the last 100 years and determine which has been the most significant for both guests and hotel owners. Explain your rationale.
Determine how evolving communications technology (i.e., cell phones and Wi-Fi) has changed guest expectations regarding communications, as well as how the lodging industry should respond.
WRITE MINUMUM 4 SENTENCES FOR EACH PARAPGRAPH. PROVIDE ORGINAL WORK. WRITE THEM ON YOUR OWN WORDS. GONNA USE TURNITIN TO CHECK PLAGARISIM. TYPE EACH QUESTION BEFORE ANSWER THEM.
.
Evolving Health Care Environment and Political ActivismRead and .docxturveycharlyn
Evolving Health Care Environment and Political Activism
Read and watch the lecture resources & materials below early in the week to help you respond to the discussion questions and to complete your assignment(s).
(Note: The citations below are provided for your research convenience. Students should always cross reference the current APA guide for correct styling of citations and references in their academic work.)
Read
Black, B. P. (2017). Chapter 14 and 15
Online Materials & Resources
Lucas, A. & Ward, C. W. (2016). Using social media to increase engagement in nursing organizations. Nursing, 46(6), 47-49.
Johnson, J. E. & Billingsley, M. (2014). Convergence: How nursing unions and Magnet are advancing nursing. Nursing Forum, 49(4), 225-232
Berg, J. G. & Dickow, M. (2014). Nurse role exploration project: The Affordable Care Act and new nursing roles. Nurse Leader, 12(5), 40-44
Vincent, D. & Reed, P. G. (2014). Affordable Care Act: Overview and implications for advancing nursing. Nursing Science Quarterly, 27(4), 254-259.
QUESTION
What are your thoughts about the debate regarding whether health care is a right or a privilege? How has the changing health care environment impacted your practice?
Submission Instructions:
Your initial post should be at least 500 words, formatted and cited in current APA style with support from at least 2 academic sources.
Your assignment will be graded according to the grading rubric.
.
Evolving Families PresentationPrepare a PowerPoint presentatio.docxturveycharlyn
Evolving Families Presentation
Prepare a PowerPoint presentation to explore how families have changed over time. Be sure to include the contributors to the various changes. The presentation should consist of at least eight (not to exceed 10) slides as described below:
Slide 1: Introduction
Slide 2: A
narrative
discussing
how the family has changed
over time? Explicitly note what changes have occurred.
Slide 3:
Visual depictions
of what the
"typical" family used to look like
. You are welcomed to use a range of media resources.
Slide 4:
Visual depictions
of what the
"typical" family looks like now
. (i.e., how do you perceive or define the typical family, how does society perceive or define the typical family, etc.) You are welcomed to use a range of media resources.
Slide 5: A
narrative
discussing and analyzing the
individual factors
that have contributed to the changing family. (See your textbook. You may use external resources as well.)
Slide 6: A
narrative
discussing and analyzing the
systemic or structural factors
that have contributed to the changing family over time. (See your textbook. You may use external resources as well.)
Slide 7:
Conclusions
Slide 8:
Citations/Resources
.
EvolutionLets keep this discussion scientific! I do not want .docxturveycharlyn
"Evolution"
Let's keep this discussion scientific! I do not want to have a debate about anyone's religious views on this topic.
Please respond to one of the following discussion topics with a primary post of at least 125 words. Additionally, please make a substantive reply to a fellow student.
•
(1) Read the
article
by Marris (2014) on “How a few species are hacking climate change”. Based on this article, explain the difference between “phenotypic plasticity” and “genetic evolution”. When species change over time, how can we tell the difference between these two mechanisms?
.
Evolutionary Theory ApproachDiscuss your understanding of .docxturveycharlyn
Evolutionary Theory Approach
Discuss your understanding of the theory of evolution. Explain how the concept of natural selection might be applied to the development of personality
Genetic/biological Approach
Develop two goals for a client with ADHD using the genetic and biological theories of personality development. Explain how these goals utilize the genetic and/or biological theories.
Explain how Eysenck’s approach compares with the other theories related to genetic and biological aspects of personality development. What are the benefits of each of these theories?
.
Evolution or change over time occurs through the processes of natura.docxturveycharlyn
Evolution or change over time occurs through the processes of natural and sexual selection. In response to problems in our environment, we adapt both physically and psychologically to ensure our survival and reproduction. Sexual selection theory describes how evolution has shaped us to provide a mating advantage rather than just a survival advantage and occurs through two distinct pathways: intrasexual competition and intersexual selection. Gene selection theory, the modern explanation behind evolutionary biology, occurs through the desire for gene replication. Evolutionary psychology connects evolutionary principles with modern psychology and focuses primarily on psychological adaptations: changes in the way we think in order to improve our survival. Two major evolutionary psychological theories are described: Sexual strategies theory describes the psychology of human mating strategies and the ways in which women and men differ in those strategies. Error management theory describes the evolution of biases in the way we think about everything. Learning Objectives • Learn what “evolution” means. • Define the primary mechanisms by which evolution takes place. • Identify the two major classes of adaptations. • Define sexual selection and its two primary processes. • Define gene selection theory. • Understand psychological adaptations. • Identify the core premises of sexual strategies theory. • Identify the core premises of error management theory, and provide two empirical examples of adaptive cognitive biases. Introduction If you have ever been on a first date, you’re probably familiar with the anxiety of trying to figure out what clothes to wear or what perfume or cologne to put on. In fact, you may even consider flossing your teeth for the first time all year. When considering why you put in all this work, you probably recognize that you’re doing it to impress the other person. But how did you learn these particular behaviors? Where did you get the idea that a first date should be at a nice restaurant or someplace unique? It is possible that we have been taught these behaviors by observing others. It is also possible, however, that these behaviors— the fancy clothes, the expensive restaurant —are biologically programmed into us. That is, just as peacocks display their feathers to show how attractive they are, or some lizards do push-ups to show how strong they are, when we style our hair or bring a gift to a date, we’re trying to communicate to the other person: “Hey, I’m a good mate! Choose me! Choose me!" However, we all know that our ancestors hundreds of thousands of years ago weren’t driving sports cars or wearing designer clothes to attract mates. So how could someone ever say that such behaviors are “biologically programmed” into us? Well, even though our ancestors might not have been doing these specific actions, these behaviors are the result of the same driving force: the powerful influence of evolution. Yes, evolution—certain trait.
Evolution, Religion, and Intelligent DesignMany people mistakenl.docxturveycharlyn
Evolution, Religion, and Intelligent Design
Many people mistakenly believe that a belief in evolution precludes a belief in God or intelligent design; in other words, some people falsely think that one must be an atheist or agnostic to believe in evolution and the Big Bang. The Catholic Church is one example of a religious institution that has long held the view that evolution and the Big Bang explain ‘how we got here.’ Read the below article from the
Catholic Herald
, and then answer the following questions: Why do you think so many people are mistaken about the ability to believe in God as well as evolution and the Big Bang? Do you find anything problematic about combining religious and scientific explanations of the universe? Explain.
NB: In this discussion, students often misuse the word ‘theory’, saying things such as “the Big Bang/evolution are ‘just’ theories.” But to say this is a misuse of the word 'theory' as it applies to scientific theory. Many people misunderstand the word as it is used in the realm of science, thinking it to mean a guess, a hypothetical, untested idea. However, in science, 'theory' means something different. Please read the article below:
"Just a Theory": 7 Misused Science Words - Scientific American
Article from the
Catholic Herald
By Patrick Cusworth October 31, 2014
Pope Francis's comments on the Big Bang are not revolutionary. Catholic teaching has long professed the likelihood of human evolution
Perhaps it was inevitable that Pope Francis’ comments on the Church’s position on scientific theories such as the Big Bang and evolution would cause a stir. In his address to the Pontifical Academy of Sciences, the Pope cautioned against the image of God the creator as “a magician, with a magic wand”, arguing that belief in both theories around the beginnings of the universe and the birth of humankind are consistent with the Catholic faith.
“The Big Bang, which is today posited as the origin of the world, does not contradict the divine act of creation; rather, it requires it”, he stated. Similarly, he argued, “evolution of nature is not inconsistent with the notion of creation because evolution pre-supposes the creation of beings which evolve.”
Yet despite further murmurings that Pope Francis was beginning (yet another) revolution in Catholic doctrine, it must be pointed out – the Pope’s declaration on either theory has not broken with established Catholic belief in the slightest.
The Big Bang theory, originally hypothesised in 1927 by Jesuit priest and physicist Georges Lemaître, is based on the central proposition that the universe is continually expanding. As a preposition, the universe was originally contained within a single point, in a highly intense state of heat and density. As the universe began to expand it cooled, allowing the formation of subatomic particles, which began a series of physical cosmological processes, which led eventually to the known universe. While this has become the most co.
Evolution and Its ProcessesFigure 1 Diversity of Life on Eart.docxturveycharlyn
Evolution and Its Processes
Figure 1: Diversity of Life on Earth
The diversity of life on Earth is the result of evolution, a continuous process that is still occurring.
“wolf”: modification of work by Gary Kramer, USFWS; “coral”: modification of work by William Harrigan, NOAA; “river”: modification of work by Vojtěch Dostál; “protozoa”: modification of work by Sharon Franklin, Stephen Ausmus, USDA ARS; “fish” modification of work by Christian Mehlführer; “mushroom”, “bee”: modification of work by Cory Zanker; “tree”: modification of work by Joseph Kranak
Chapter Outline
1. Discovering How Populations Change
2. Mechanisms of Evolution
3. Evidence of Evolution
4. Speciation
5. Common Misconceptions about Evolution
Introduction
All species of living organisms—from the bacteria on our skin, to the trees in our yards, to the birds outside—evolved at some point from a different species. Although it may seem that living things today stay much the same from generation to generation, that is not the case: evolution is ongoing. Evolution is the process through which the characteristics of species change and through which new species arise.
The theory of evolution is the unifying theory of biology, meaning it is the framework within which biologists ask questions about the living world. Its power is that it provides direction for predictions about living things that are borne out in experiment after experiment. The Ukrainian-born American geneticist Theodosius Dobzhansky famously wrote that "nothing makes sense in biology except in the light of evolution" (Dobzhansky 1964, 449). He meant that the principle that all life has evolved and diversified from a common ancestor is the foundation from which we understand all other questions in biology. This chapter will explain some of the mechanisms for evolutionary change and the kinds of questions that biologists can and have answered using evolutionary theory.
Discovering How Populations Change
By the end of this section, you will bbe able to:
· Explain how Darwin’s theory of evolution differed from the current view at the time.
· Describe how the present-day theory of evolution was developed.
· Describe how population genetics is used to study the evolution of populations
The theory of evolution by natural selection describes a mechanism for species change over time. That species change had been suggested and debated well before Darwin. The view that species were static and unchanging was grounded in the writings of Plato, yet there were also ancient Greeks that expressed evolutionary ideas.
In the eighteenth century, ideas about the evolution of animals were reintroduced by the naturalist Georges-Louis Leclerc, Comte de Buffon and even by Charles Darwin’s grandfather, Erasmus Darwin. During this time, it was also accepted that there were extinct species. At the same time, James Hutton, the Scottish naturalist, proposed that geological change occurred gradually by the accumulation of small changes from pr.
Evolution in Animals and Population of HumansHumans belong t.docxturveycharlyn
"Evolution in Animals and Population of Humans"
Humans belong to the genus Homo and chimpanzees to the genus Pan, yet studies of primate genes show that chimpanzees and humans are more closely related to one another than each is to any other animals. In light of this result, some researchers suggest that chimpanzees should be renamed as members of the genus Homo. Discuss at least three (3) practical, scientific, and / or ethical issues that might be raised by such a change in naming.
.
Evolution of Seoul City in South KoreaHow the City changed s.docxturveycharlyn
Evolution of Seoul City in South Korea
How the City changed since it was first created. Describe the changes over time up to the present day.
Note
: Insert Citations at the final slide
include pictures of city (not the people in the city)
and you should have enough information ( only takes about the city, Don't talk about the people)!!!!
6 slides
.
evise your own definition of homegrown terrorism. Then using t.docxturveycharlyn
evise your own definition of homegrown terrorism. Then using the e-Activity, provide one example of what you believe to be a specific homegrown terrorist attack that occurred in the United States. Provide a rationale for your response.
There are many agencies, including private security, directly involved in defending against homegrown terrorism that are not part of the Department of Homeland Security (DHS). Examine at least three agencies that are not part of the DHS but play a direct role in homeland security. Hypothesize the key reasons why you believe these three agencies are not part of the DHS. Justify your response.
.
eview the Paraphrasing tutorial here (Links to an external sit.docxturveycharlyn
eview the Paraphrasing tutorial
here (Links to an external site.)
. There's also a helpful video
here (Links to an external site.)
.
Directions
: Paraphrase the quote below by putting into your own words
"I am most willing to answer all questions about myself. I have nothing to hide from your committee and there is nothing in my life of which I am ashamed. I have been advised by counsel that under the fifth amendment I have a constitutional privilege to decline to answer any questions about my political opinions, activities, and associations, on the grounds of self-incrimination. I do not wish to claim this privilege. I am ready and willing to testify before the representatives of our Government as to my own opinions and my own actions, regardless of any risks or consequences to myself."
Excerpt from Lillian Hellman,
Letter to HUAC (Links to an external site.)
, May 19, 1952.
you need to put this in your own words. So, take it out of the quote. Don't forget to cite!
Type your answer into the text box below.
.
Evidenced-Based Practice- Sample Selection and Application .docxturveycharlyn
Evidenced-Based Practice- Sample Selection and Application
Description: Professional nursing practice is grounded in the translation of current evidence
into practice.
Course Competencies: 1) Examine the relationships among theory, practice, and research. 2)
Interpret research findings using the elements of the research process. 5) Evaluate data from
relevant sources, including technology, to inform the delivery of care to culturally and
ethnically diverse populations. 6) Collaborate with health team members to collect, interpret,
synthesize and disseminate evidence to improve patient outcomes in complex health care
environments.
QSEN Competency: 3) Evidence-Based Practice
BSN Essential III
Area Gold
Mastery
Silver
Proficient
Bronze
Acceptable
Acceptable
Mastery not
Demonstrated
Fully detail how
the research
process is
sampling
dependent.
Describes
neighborhoods
that reflect the
best fit for 1-
Geriatrics 2-
South East Asians
3- Poverty 4-
Pediatrics
Fully details how
the research
process is
sampling
dependent.
Describes
neighborhoods
that reflect the
best fit for 1-
Geriatrics 2-
South East Asians
3- Poverty 4-
Pediatrics
Describes how
research and
sampling affect
generalizability of
findings but does
not identify
specific
populations in
Sentinel City®
Superficially
describes
sampling but does
not connect to
generalizability of
research findings
to practice
Identifies
populations of
interest but does
not relate to
research
applicability
Fully detail, with
specific
example(s), inter-
professional
evidence-based
practice guidelines
and states
outcomes specific
to one area of
choosing 1-
Geriatrics 2-
South East Asians
3- Poverty 4-
Pediatrics
Fully details, with
specific
example(s), inter-
professional
evidence-based
practice guidelines
and states
outcomes specific
to one area of
choosing 1-
Geriatrics 2-
South East Asians
3- Poverty 4-
Pediatrics
Describes, with
specific
example(s) inter
professional
evidence-based
practice guidelines
but does not
develop outcomes
specific to a
population
Superficially
describes with
what evidence-
based practice
guidelines are
available but does
not address
interprofessional
nature or
outcomes
Provides
suggestions to
improve care for
population but
provides no
research/evidence
to support
APA, Grammar,
Spelling, and
Punctuation
No errors in APA,
Spelling, and
Punctuation.
One to three errors
in APA, Spelling,
and Punctuation.
Four to six errors
in APA, Spelling,
and Punctuation.
Seven or more
errors in APA,
Spelling, and
Punctuation.
References Provides two or
more references.
Provides two
references.
Provides one
references.
Provides no
references.
Include a PICO
model that clearly
labels specific
.
Evidenced-Based Practice- Evaluating a Quantitative Research S.docxturveycharlyn
Evidenced-Based Practice- Evaluating a Quantitative Research Study
Description: The baccalaureate graduate nurse will demonstrate an understanding of the basic
elements of the research process and models for applying evidence to clinical practice.
Course Competencies: 1) Examine the relationships among theory, practice, and research. 2)
Interpret research findings using the elements of the research process. 3) Differentiate between
ethical and legal precepts that guide research conduct and protect human subjects. 4) Integrate
reliable evidence from multiple ways of knowing, to inform practice and make clinical
judgments. 5) Evaluate data from relevant sources, including technology, to inform the delivery
of care to culturally and ethnically diverse populations. 6) Collaborate with health team
members to collect, interpret, synthesize and disseminate evidence to improve patient outcomes
in complex health care environments.
QSEN Competency: 3) Evidence-Based Practice
BSN Essential III
Area Gold
Mastery
Silver
Proficient
Bronze
Acceptable
Acceptable
Mastery not
Demonstrated
Evaluates
research design
of study using all
of the
components of
the evaluation
checklists in
Houser 2018, p.
345
Evaluates
research design
of study using all
of the
components of
the evaluation
checklists in
Houser 2018, p.
345
Evaluates
research design
of study using
(75%)
components of
the evaluation
checklists in
Houser (2018).
Evaluates
research design
of study using
some (50% or
less) components
of the evaluation
checklists in
Houser (2018).
Does not address
section
Evaluates
methods/procedu
re, and results of
the study using
all of the
components of
the evaluation
checklist in
Houser 2018,
p.377
Evaluates
methods/procedu
re, and results of
the study using
all of the
components of
the evaluation
checklist in
Houser 2018,
p.377
Evaluates
methods/procedu
res and results of
the study using
(75%)
components of
the evaluation
checklists in
Houser (2018).
Evaluates
methods/procedu
res and results of
the study using
some (50% or
less) components
of the evaluation
checklists in
Houser (2018).
Does not address
section
Discusses the
importance of
research, how the
study contributes
to EBP and
applicability of
the specific study
to clinical
practice
Discusses the
importance of
research, how the
study contributes
to EBP and
applicability of
the specific study
to clinical
practice
Discusses the
importance of
research and how
the study may
contribute to
EBP in general
but not how the
specific study
contributes to
current clinical
practice.
Provides simple
definitions of
research and
evidence but
does not delve
into the
relationship
among research,
evidence-based
practice and
Does not address
section
impr.
eview the Captain Edith Strong case study in Ch. 6 of Organi.docxturveycharlyn
eview
the Captain Edith Strong case study in Ch. 6 of
Organizational Behavior and Management in Law Enforcement
.
Answer
the questions in column one.
This is not an opinion paper, SO DO NOT USE FIRST OR SECOND PERSON;
your answers should be supported with the textbook readings and outside research; you need a minimum of two references and citations.
Format
your references consistent with APA guidelines.
.
Evidenced based practice In this writing, locate an article pert.docxturveycharlyn
Evidenced based practice
In this writing, locate an article pertaining to the topic below. Choose your article wisely, because you will be incorporating the article into all three of your writing assignments this session. In this writing, please discuss how this (one) article will be beneficial to your assigned topic. (The article should be a research conducted in United states.) Also state what you will be focusing on.
Topic: Preventing Healthcare Associated Infections.
This should be a page. Do not use direct quotes, but paraphrase. Also, cite the article you chose in APA 6th edition format.
Research Design: Observational
and Correlational Studies
Video Title: Research Design: Observational and Correlational Studies
Originally Published: 2011
Publishing Company: SAGE Publications, Inc
City: Thousand Oaks, USA
ISBN: 9781483397108
DOI: https://dx.doi.org/10.4135/9781483397108
(c) SAGE Publications, Inc., 2011
This PDF has been generated from SAGE Research Methods.
https://dx.doi.org/10.4135/9781483397108
NARRATOR: Research Design-- Observational and Correlational Studies. Since the moment you
were born, you've been exploring the world around you. In a sense, you've been conducting research.
You've noticed the ways people interact with each other, the relative sizes of objects,
NARRATOR [continued]: and how the colors of nature change with the seasons. Each of us is an
amateur researcher, observing, analyzing, and drawing conclusions about everything we see. In order
to conduct a more formal study whose conclusions you can share with others, you need to apply
scientific methods to your research.
NARRATOR [continued]: Knowing about scientific research methods will also help you understand,
interpret, and be more analytical in your thinking about studies you read about in textbooks, journals,
newspapers, or online. To make sure your research is as strong as possible, let's talk about designing
your study and interpreting your results.
NARRATOR [continued]: Specifically, we'll focus on some overarching types of research studies,
when to use an observational design, along with some advantages and disadvantages, two different
types of observational design, those that you conduct in the field and those that you conduct in a
laboratory,
NARRATOR [continued]: analyzing data from an observational study, including some statistical
methods, when to use a correlational design, along with some advantages and disadvantages, how
to design and implement one, and analyzing data from a correlational study.
NARRATOR [continued]: Before we begin to explore research designs, it is important to understand
the terms "variable" and "construct." These terms are used interchangeably and are found throughout
scientific literature.
NICOLE CAIN: A "construct," which can also be called a "variable," is a topic of interest that varies
from person to person. Some examples of constructs that researchers .
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
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Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Transcript PHY 21041 Lab 8 Hi again! Well back in Lab 4, y.docx
1. Transcript: PHY 21041 Lab 8
Hi again! Well back in Lab 4, you measured the speed of sound
in two different ways.
That’s quite an accomplishment because sound travels as fast as
a bullet or a jet plane.
In this lab, your mission‐ should you decide to accept it‐ is to m
easure the speed of light!
Light‐ about a million times faster than sound. And it may soun
d crazy, but one way to
do that‐to measure the speed of light‐ is to use a microwave safe
plate, and uh,
marshmallows, or chocolate chips, or a candy car. This one fell
over. I’ll just eat.
Okay, not the speed of light, exactly, but of microwaves, a cousi
n of light. Use an
ordinary microwave oven, take out the tray inside and the roller
mechanism, so it won’t
rotate, put the plate of marshmallows or chocolate inside, set it
for about thirty seconds
or so and let it run. What you’ll see when you take the plate out
, is little melted spots in
the marshmallows or chocolate. They correspond to the locatio
ns of the antinode of
the standing wave inside the oven. You want to measure the dis
tance in centimeters
between those hot spots as accurately as you can, then follow th
e directions in Learn.
And believe it or not, you’ll be able to calculate the speed of mi
crowaves, and the speed
of light! You’ll also see from this of course, why it is that mic
rowave ovens have those
2. turntables to move the food through those antinode hot spots to
heat it more evenly.
We have a more high‐tech way to measure the speed of light dir
ectly, as well, with this
equipment. On the left we have a precision, high speed oscillos
cope. In the center; a
speed of light module kit; on the right side, a spool of 20 meters
of fiber optic cable‐ it
looks like wire, but it’s actually plastic fiber. Here we have a li
ttle light emitting diode
that gives off very brief, very rapid pulses of light. If you look
ed inside the hole, here,
you’d see a steady red light because it happens too fast for us to
see.
The light travels out of here, around and around and around this
fiber optic cable‐ 20
meters of cable, a little more than 60 feet of cable, comes back i
n here, where if you
see, by a photo transistor. All this circuitry just runs these two
devices here. These
wires bring the signals over to the oscilloscope.
On the oscilloscope, the top track shows the pulse as being sent
out, and the bottom
track or graph shows the pulse being received. There will be a
picture of this in the
instructions on Learn, and from that you’ll be able to measure t
he time delay between
here and here. That’s the time it took for light to travel 20 mete
rs. It’s amazing we can
measure something as fast as light going in such a short distanc
e as 20 meters, just
amazing!
3. macaulay.cuny.edu
Kent State University
Act IIILab 8 Lab 8
Measuring the speed of light
The idea: Part 1 of this lab is short and sweet – literally! Part
2 is not bad either.
There is something special about the speed of light. No object
can ever
travel that fast. Not even an electron, the smallest bit of matter
we
know, can move that fast; there is not enough energy in the
entire
universe to make even one electron move at the speed of light.
But light
can travel that fast, because it is not an object. Light is a
phenomenon,
electric and magnetic fields tumbling over each other, re-
creating each
other, through space.
Now when physics folks say ‘light,’ they mean – besides ‘not
heavy’ –
light that we can see, plus all the relatives of light, other
electromagnetic
waves. Gamma rays, X-rays, ultraviolet, visible and infrared
light,
microwaves, and radio waves – they are all the same
phenomenon, but
of different frequency. And since we know that the medium,
4. not the
frequency, determines the speed of a wave, if we can measure
the speed
of any of those forms, we know the speed of all of them.
Your microwave oven creates electromagnetic waves of a
known
frequency. In Part 1 of this lab you will measure their
wavelength, and
can then easily calculate their speed. In Part 2 you will measure
the
speed of visible light, using data from an electronic apparatus,
and an
oscilloscope stretched to its limit. Let’s go!
What you’ll learn: By the end of this you will understand why
most microwave ovens have
rotating turntables. More related to this course, you will learn
1) how to measure the wavelength of a microwave,
2) two ways to calculate the speed and expected speed of light,
and
3) how to do calculations involving index of refraction.
8.1
What you’ll need: Microwave oven
Small metric ruler
Calculator
Microwave-safe glass dish or paper plate
Miniature marshmallows or chocolate chips or a large chocolate
bar
Image of an oscilloscope screen
5. What you’ll do: Part 1
1) Remove the turntable and the bearing ring from your
microwave
oven. See if you can find a shallow, rectangular glass dish that
fits nicely
in the microwave oven. If not, a paper or foam plate will do.
2) Line the dish with marshmallows standing on their ends, one
layer
thick. Or tile over the paper plate with marshmallows standing
on end.
Or, spread a thin layer of chocolate chips over a paper or foam
plate, or,
unwrap a large chocolate bar and place it on a paper plate.
Whatever you chose to use, place it in the microwave oven and
heat for
a few seconds at a time until you see the marshmallows or
chocolate
start to soften or melt in certain hot spots. Don’t heat too long,
or the
hot spots will grow and become difficult to measure.
3) Remove the dish or plate from the oven and carefully
measure from
the center of one hot spot to the center of the next, in cm. You
may you
need to make several measurements and average them out. Or
you may
decide to eat the marshmallows or the chocolate and start over.
That’s
fine with me. But seriously, record the distance between the hot
spots
on the Report Sheet.
6. 4) The hot spots appear at the antinodes of the standing wave
that
forms inside the oven. As with any standing wave, the distance
between
two successive antinodes is one-half wavelength. Double the
measurement from Step 3, convert it to meters, and record that
measure
of the wavelength on the Report Sheet. You are almost done
already!
5) Look up on the internet the frequency of the microwaves
produced in
microwave ovens. You may find the answer in terms of
Gigahertz
(billions of hertz) or Megahertz (millions of hertz). Whichever
you
found, multiply by a billion or a million, respectively, to
convert the
frequency to Hz and record that number.
8.2
6) Finally, multiply the frequency from Step 5 times the
wavelength
from Step 4. Round to two digits and the correct number of
zeroes and
record it in the table on the Report Sheet.
Technically, we have measured the speed of microwaves, and
therefore
light, through air. The value is only three-hundredths of a
percent lower
than the speed of light in a vacuum, and that is well within the
range of
7. experimental error, so we can ignore the difference.
Part 2
In this part of the lab you will measure the speed of light rather
passively, I’m afraid, as this lab is not conducive to controlling
by remote
access, as you did in Labs 3 and 7.
In Smith Hall we have electronic kits that produce a series of
extremely
short pulses of laser light from the blue upper connector on the
right
side. They travel through a 20.0 m long piece of fiber optic
cable, and
are received by a detector in the lower black connector on the
right side.
A high speed oscilloscope monitors both the outgoing and
incoming
signals through those two long black connectors that you see in
the
photo.
∫ to a 20 m long
spool of fiber
optic cableª back from the
spool of cable
8.3
The upper channel trace on the oscilloscope screen below
displays a
frog-on-a-post graph of the light pulses as they are emitted, and
the
8. lower line on the oscilloscope shows the pulses as they are
received.
If light traveled infinitely fast, the peaks in the two
traces would line up. But even though the speed of
light is the fastest known speed in the universe, it is
not infinite! Light takes a tiny bit of time to travel
any distance, even 20 meters.
As a result, the lower trace on the screen is shifted a
little to the right. The difference in the position
of the two peaks tells the time for light to travel
20.0 m.
7) Open and print the enlarged image of the oscilloscope
screen, in the
same item as these instructions. Use the time scale information
on that
page, and as carefully as you possibly can, estimate the time
delay
caused by passing the light through the cable. Record that time,
in
seconds, on the Report Sheet.
8) Calculate the speed of light in the plastic cable, knowing that
it
traveled 20.0 m in the time you just found in step 8.
9) There is just one complication. Light travels more slowly in
any
material, such as the plastic in this cable, than in a vacuum.
The speed
of light in some substance is related to the speed of light in a
vacuum, c,
by this expression:
9. n = speed of light in vacuum/speed of light in some material
n = c/v
where v is the speed of light in a material and n is called the
index of
refraction of the that material. Think of n as the slowing-down
factor,
or how strongly light is bothered or pestered by the medium –
how
much light is affected by it.
The manufacturer of the fiber optic cable reports that the value
of n for
their cables is 1.25. Use that value along with your
measurement of the
speed of light in the cable to estimate the speed of light in a
vacuum, c,
and record it.
8.4
10) You know from the companion class that the speed of light,
to two
decimal places, is 3.00 x 108 m/s, or 300,000,000 m/s.
Calculate the
percent difference between each of your estimates for the speed
of light,
from Parts 1 and 2, and that known speed. Enter those percent
differences on the Report Sheet
Web extension
One of the best measurements ever made of the speed of light
10. was
accomplished by Albert Michelson and E. W. Morley at what is
now Case
Western Reserve University in Cleveland. Find out what year
they made
that measurement, and the value they found for the speed of
light.
Be sure to include the web address of the site where you found
the
information.
8.5
Kent State University
Act IIILab 8
Measuring the speed of lightReport sheet
Name Objective: To 1) measure the wavelength of a
microwave, 2) calculate the speed of light in two ways, and3)
perform calculations involving index of refraction.Data: Part 1
Distance between hot spots,cmWavelength of
microwave,cmWavelength of microwave,m
Frequency of microwaves,Ghz or MhzFrequency of
microwaves,HzSpeed of microwaves andspeed of light, m/s
Part 2
Number of small ticksbetween peaksTime between peaks, s
Speed of light in the fiberoptic plastic, m/sSpeed of light in
vacuum,m/sPercent difference fromknown speed, Part 1Percent
11. difference fromknown speed, Part 2
Comment on why either method (Part 1 or Part 2) may be more
accurate.
Web extensionWhen did Michelson and Morley, in Cleveland,
make their precisemeasurement of the speed of light?
What did they measure for its speed?What source did you
consult for your answers?
PR Photo (Proof you Really did the experiment)Upload a photo
of you with the melted marshmallows or chocolate.
Kent State University
Act IILab 4
Lab 4
Measuring the speed of sound
Report sheet
Name
Objective: To 1) measure the speed of sound outdoors, 2)
capture a wave and measure its wavelength, and 3) demonstrate
that the speed of sound depends on the medium through
which it travels.
Data:
Table for Part 1
12. Time for sound to travel, sDistance sound traveled, mSpeed of
sound, m/sAir temperature outdoors, oC
Table for Part 2
Frequency, f,
Hz
Length of air
column, L, cm
Length of air
column, L, m
Wavelength, ë,
m
Speed of sound,
m/s
Average
Air temperature indoors, oC
For both parts
Your expected speed of sound for Part 1, based on the air
temperature, m/s
Your expected speed of sound for Part 2, based on the air
temperature, m/s
Which of the methods in this experiment came closer to the
expected speed of sound?
Why might you expect one of these methods to be more or less
accurate than the other?
13. Web extension
In your search of the internet, who do you think should get
credit for theearliest measurement of the speed of sound?
When did that person make the measurement?
How did he or she make the measurement?
PR Photo (Proof you Really did the experiment)
Submit a photo of you performing either part of this experiment.
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14. macaulay.cuny.edu
Kent State University
Act II
Lab 4
Lab 4
Measuring the speed of sound
The idea: By our standards, sound travels super fast, about the
speed of a fast
bullet. Even so, we can measure that speed in the lab. Today
you will
measure the speed of sound in two ways. The first takes
advantage of
the distance learning format and the wide open spaces outside a
conventional laboratory (Part 1). The other is a clever indirect
method
(Part 2) that students use in the face-to-face version of this
course.
What you’ll learn: By the end of this experiment you will
understand
1) how to measure the speed of sound outdoors,
2) how to capture a wave in a pipe and measure its wavelength,
and
3) that the speed of sound depends only on the medium through
which
it travels.
What you’ll need: Part 1
Stopwatch or stopwatch function on your phone
Bell tower that chimes on the hour
15. Part 2
Deep bucket or sink
Piece of plastic pipe or other tube
Pencil and ruler
Computer with headphones or earbuds and Audacity program, or
a tone
generator app on your smartphone
Willing assistant
3.1
What you’ll do: Part 1
1) This direct method works if you live in or near a town that
has a bell
tower that chimes on the hour, perhaps on a city building or a
church. If
you don’t, come to Kent for a morning or afternoon. Kent has
two
chimes – the University Library, and St. Patrick’s Church on N.
DePeyster Street, just east of downtown. With a stopwatch or
other
timer that will run for more than an hour, stand as close to the
tower as
you can, just before any given hour. Decide when in the cycle
of chimes
to start your timer. Both towers in Kent play the four-line
Westminster
chime before the actual gongs for the hour, so if I were doing
the
experiment, I would use the Westminster chime as a ‘get-ready’
signal,
and then start timing on the first gong following the chimes.
16. Let the
timer run; do not disturb it!
2) Go to a place in town where you can hear the tower from
some
distance, at least a few blocks, away. For a good guideline, if
you can
still see the tower or church but in the distance, you are
probably in a
good spot. Have lunch or talk with a friend for a while. Then,
just before
the next hour, wait for the same chime sequence and stand
ready. At
the same point in the cycle as before, stop the timer.
Now, had you been in the same place both times, your timer
would read
exactly one hour. But it won’t, since you moved a distance
away from
the tower. The extra time is the time required for the sound of
the
gong to travel the distance between the tower and your new
location. In other words, subtract one hour from the time you
measured, and that is the travel time for the sound. Record that
time, in
seconds, on the Report Sheet.
3) At your convenience go to Mapquest or Google Maps on
your
computer and generate a map that includes both the tower
location and
the spot where you stood an hour later. Locate them precisely
on the
map; it may help to print it out and mark the spots carefully on
the
printed map. Measure the distance between the two points as
17. accurately as possible using a metric ruler. Then measure the
length of
the metric distance scale on the map. Set up a simple
proportion:
number of meters on distance scale distance from tower
-------------------------------------- = ------------------------------
length of distance scale on map distance on map
3.2
A portion of the Google Maps image for Kent State University.
The lower red X marks the
location of the bell tower, where the chimes are housed. The
upper X designates where I was
standing while recording the introductory video for Lab 4.
Notice the distance scale in the
red oval.
Cross-multiply and solve for the distance from the tower. We
want the
distance in meters, and as you see from inside the red oval on
this map,
Google Maps measures in feet. But that is no problem for
Physics
students! Simply divide the number of feet that the sound
traveled by
3.28 feet per meter. Record that distance on the Report Sheet.
4) Divide the distance from Step 3 by the time from Step 2, and
round
off to a whole number. That’s one estimate of the speed of
sound.
18. 5) Find and record the outside air temperature in oC. If you can
only
find the temperature in oF, check Google for how to convert the
temperature to oC.
Part 2
6) You know that for any wave, v = f ë. Here you will use a
computer
program or a phone app to make a sound wave with a known
frequency,
and a wavelength that you can measure. Multiplying those
together
gives the speed of the wave.
3.3
Resonance is that easy transfer of wave energy from one object
to
another when the frequencies match. One object is an earbud or
phone
producing a sound of known frequency, and the other is a
column of air
in a small piece of plastic pipe or other tube, where you will
adjust the
length of the air column until its frequency matches the tuning
fork.
You’ll know they match because the air in the pipe will ‘sing
along’ with
the earbud!
If you happen to have some plastic pipe around the house, from
3/4" to
2" diameter and a pipe cutter, lop off a section about 18 inches
19. (or 45
cm) long. Now don’t laugh; some people out there will actually
have
that lying around. For those of you who do not include pipe
cutters
among your possessions, you have many inexpensive options.
Lowes
and Home Depot both sell two-foot long sections of plastic pipe
of many
different diameters. Lowes also has a great item for this
experiment, a 16
inch long straight piece of plastic pipe for sink drain repairs.
Even cheaper, and more available for some of you, is the plastic
tube
that some golfers use in their golf bags to keep the club shafts
from
rattling into one another. You can buy a long tube for only a
couple of
dollars and cut it into 16 in or 18 in long pieces with good
scissors or a
razor knife. Any sporting goods store will carry those tubes.
You could even use the cardboard tube from a roll of paper
towels. It
will get soggy, but will last long enough for your purposes.
And in case none of those will work for you, we have included
in your
free packet for this course a sheet of transparency film that you
can roll
into a straight tube about an inch or two in diameter, and then
tape
closed along the edge.
You’ll also need a container of water about as deep as the pipe
20. is long.
You may have a bucket around, or a deep washtub sink. The
five gallon
paint buckets that both Lowes and Home Depot sell for only a
few
dollars are great – and useful for lots of other stuff after the
course is
done.
Do you have a tall vase? That would be perfect. Or an
aquarium? Or a
bathtub? Depending on its design, you could even use a toilet –
everybody has one of them. Be sure to flush first!
The more shallow the container, the higher the frequencies you
will
have to use, because you already know that the higher the
frequency,
3.4
the shorter the wave. Remember, it’s not the width or volume
of the
container that matters, only the depth.
7) Fill the container or sink so that the water is almost as deep
as
whatever pipe or tube you are using. If you use the
transparency sheet
in the packet, hold it gently so that it stays round, and keep the
zero end
of the scale printed on it toward the top.
8) Plug headphones or earbuds into the audio output of your
21. computer. Run the Audacity program that you used previously,
but now
you will use it to generate a tone. Click Generate, then Track.
In the
pop-up, choose Sine and an amplitude of 1. Enter a frequency
in the
approximate range of 180 Hz to 500 Hz, then click OK. Record
the
frequency in the data table on the Report Sheet for this lab.
If you have a smart phone, you could also download any free
app that
generates musical tones. For my Android phone, I found one
called –
guess what? – Tone Generator. In that case you would hold the
speaker
of the phone above the tube, in place of the computer
headphone, as
pictured.
9) Click the Play button (|) in Audacity, or have a friend click
it. With
one hand, hold the pipe straight up so that the lower end is just
under
the water. With the other, hold the headphone or earbud at the
upper
end of the pipe. If you are using a headphone, leave a little
space
between it and the upper end of the pipe, as shown.
Then smoothly and gradually slide the plastic tube and
headphone
downward, together as one unit, until you suddenly hear a
louder sound.
It’s louder because the air in the pipe is now in resonance with
the
22. headphone! You could say that the air inside the tube is
singing along
with the headphone, so the sound is louder. Move the pipe up
and
down just a little to find the loudest resonance. While you hold
very
still, your assistant can use a pencil to mark the water level on
the plastic
tube, as accurately as possible. Then you can stop the
annoying sound
source.
10) If you are using the tube you rolled up from your packet,
you or your
assistant can measure the level of the water right on the printed
scale. If
you are using any other kind of tube, remove it from the water
and
measure and record the length of the air column in the tube,
which is
the distance from the top of the tube down to the pencil mark.
It’s better
to measure in centimeters, but if you must use inches, multiply
the
3.5
Since the pens lie diagonally,
a pen a little longer than the
cup still fits inside it. In the
same way, we have to allow for
the diameter of the pipe that
‘holds’ the wave.
23. shopapt.com
length by 2.54 cm/in, and record it in the second column in the
table, L
in cm.
11) Divide the length of the air column that you measured by
100, to
change the units to meters, and record that number in the third
column.
In a pipe closed at the bottom, only one-fourth of the wave is
caught in
the pipe in the fundamental mode. So, you should be able to
multiply
the length of the air column by four to find the wavelength.
Now I wrote ‘should’ because in fact a pipe such as this one
holds exactly
one-fourth of a wave only if the pipe is very narrow compared
with the
wavelength. (If we used such a pipe – a glass tube from
chemistry, or a
really long straw – the sound in the tube is too faint to hear.)
Acoustic
books tell us that the proper formula, including the effect of the
diameter of the pipe, looks like this:
ë = 4 (L + 0.30 d)
where L is the length of the air column in meters and d is the
inside
diameter of the pipe, also in meters.
Measure the inside diameter of the pipe you used, ideally in cm.
If you
24. used inches, multiply by 2.54 cm/in. Then divide that number
by
100 mm/m and multiply by 0.30. As an example, suppose you
used the
plastic pipe for drain repair from Lowes. It is sold as 1-1/2"
outside
diameter, but inside, I measure it as 1-3/8.” That is 1.375
inches times
2.54 cm/in, or 3.49 cm. Dividing by 100 yields 0.0349 m, and
multiplying that by 0.3 gives 0.0105 m (or 0.011 m). The
equation now
becomes
ë = 4 (L + 0.0105)
where L is in meters. Evaluate the expression and enter the
wavelength
in meters in the fourth column of the table on the Report Sheet.
12) Since v = f ë, multiply the frequency (the first column)
times the
wavelength (the fourth column) to find the speed. Round it to
the
nearest whole number and enter it in the fifth column.
13) Repeat steps 8 through 12 with four other frequencies.
Since the
speed of sound depends on the medium, the numbers in the last
column
should be about the same. Average them out and again round to
the
3.6
25. nearest whole number. Record that number, your result from
Part 1, in
the last box in the table on the Report Sheet.
14) Almost done! Find a good estimate of the indoor
temperature where
you did your experiments, in oC. If you can only find the
temperature in
oF, check Google for how to convert the temperature to oC.
Sound
propagates at 331 m/s at zero oC, plus 0.6 m/s for each degree.
For
example, at 20 oC, sound waves advance at 331 m/s plus 20
times 0.6 m/s,
or 331 m/s plus 12 m/s, or 343 m/s. See how that works?
Record the expected speed of sound for both Parts 1 and 2 on
the Report
Sheet as well.
15) Finally, evaluate your results. How well did each method
measure
the speed of sound? That is, which method produced a result
closer to
the expected speed of sound? Speculate on why that method
might have
been more reliable.
Web extension
Browsing the web, I found sites claiming that at least three
different
people first measured the speed of sound in air. Carry on the
search –
find the earliest date that someone actually measured the speed
of
26. sound. Tell me who did it, how, and when.
Be sure to include the basic web address where you found your
answer.
3.7
Transcript: PHY 21041 Lab 4
In this lab today, we’re going to measure the speed of sound in t
wo ways; one direct,
one indirect. I’m here at the base of the library tower. If you d
on’t live in Kent, find a
place where there’s a bell tower in your town and start your cell
phone stopwatch
exactly on some signal you decide. I’m going to use the first go
ng after the four‐part
Winchester chime. Let’s wait for that. Okay, here it is. I’m go
ing to start now.
Instead, you’ll go somewhere else in town where you can still h
ear the library chimes.
We’re here at the practice field by Music and Speech. When I h
ear the gong now, and
stop my watch it won’t show one hour. It will show one hour pl
us the extra few seconds
for sound to get to me from the library tower back there. Those
extra few seconds,
that’s the time for the sound to travel. Sound travels as fast as
a speeding bullet. But
even so, it will be a significant amount of time to get from back
there to over here. I
would then go to Google Maps, I’d find this location on the map
27. , I’d find the library
tower on the map, and use the scale on the computer to figure o
ut the exact distance
from there to here. I’d divide that by those extra few seconds, a
nd just like that, with
the power of physics, there is the speed of sound.
Let’s go back inside for the second part of our lab. In the rest o
f Lab 4 we’re going to
measure the speed of sound in a really clever, indirect way. We
’re going to catch a
wave, or at least part of a wave and measure its wavelength. An
d from that calculate its
speed. Here are some of things you’re going to need. First you
’ll need a sun source that
will make a reliable frequency. I downloaded a little signal gen
erator app on my phone.
You can also use your laptop with the Audacity program that yo
u’ve downloaded. And
either a computer speaker, or maybe better yet an ear bud or hea
dphone. You need a
container of water. This is a giant, cool vase I happen to have a
t home. Anything that’s
about a foot deep will do. You could use a bucket, a deep sink,
or even an aquarium,
the fish probably wouldn’t mind too much. You need some kin
d of a pipe or tube. You
could buy a very inexpensive piece plastic from Lowe’s or Hom
e Depot. You could even
use the cardboard tube from a paper towel roll, toilet paper wou
ld be too short, but a
paper towel roll could work. It will get soggy, but it will last lo
ng enough to do the
experiment. And we have also, is supplied in the kits you’ll hav
e for this class, is a piece
of plastic transparency film. With a piece of tape, you can mak
28. e it into a pipe. And use
a ruler to measure the length of the pipe and its diameter.
Let me show you what to do, how you can capture a wave and m
easure the speed of
sound. You may have a tube or type of some kind already. If y
ou want to make one
from this sheet we gave you, just roll this up long ways. It does
n’t matter exactly what
diameter you use, all that matters is that it’s not real big or real
small. And you want it
to be as straight as possible, so it isn’t wider at one end than it i
s at the other. You can
just roll this up and tape it closed. And you have a tube just lik
e that, that you can use.
This will show better on camera, I’m going to use this one inste
ad. Set your sound
source for any frequency of about 320 hertz or higher. I have m
y phone set to generate
a tone of 400 hertz.
What I’m going to do is hold speaker with my thumb. If you’re
using your laptop, you
can use a headphone or ear bud at this location. Hold it a little
bit above the end of the
tube, and the lower it down into the water. You’ll hear somethi
ng remarkable. Let’s try
this.
Ah‐ha! At one point the sound will be a lot louder. Why becau
se you’re hearing two
sound sources; this one, plus the air inside singing along at the
same frequency. This is
29. another example of resonance, the easy transfer of energy to one
medium to another.
What you want to do is fine tune this. Move this up and down g
radually, until you hear
the loudest possible sound. You may need a friend to help you,
then, to measure how
long this is and to get the most precise measurement you can.
You’ll also need to measure the inside diameter‐not the outside‐
the inside diameter of
the pipe or tube or whichever you use. We need to know how bi
g this is across, on the
inside. And do this as accurately as you can in centimeters and
millimeters.
From the lab directions, you’ll see what to do with those measur
ements to figure out
the speed of sound in its clever, indirect way.
Now the speed of sound depends on temperature as well. You’ll
need to know the
temperature of the room where you’re doing the experiment or t
he temperature of the
air outside when you do that part of the experiment inside.
Have fun!
Kent State University
Act III
Lab 10
30. Lab 10
Exploring color addition and
subtraction
Report sheet
Name
Objective: To 1) demonstrate how additive and subtractive
primary colors are related,
2) model how televisions, computer monitors, and stage lights
create
colors by combining primary colors, and
3) determine the colors needed to generate any particular
composite
color.
Data: Record the values of red, green, and blue needed to make
the colors on
the color wheel.
Red Green Blue
1) Yellow
2) Orange
3) Red
4) Crimson
5) Magenta
6) Violet
7) Blue
31. 8) Cobalt
9) Cyan
10) Turquoise
11) Green
12) Yellow - Green
9.1
Slider settings for your color, based on your birthdate:
Red Green Blue
Describe the resulting color.
Subtractive color mixing results
Incoming
light
Subtractive pigments (filters)
magenta yellow cyan magenta
+ yellow
magenta
+ cyan
33. PR Photo (Proof you Really did the experiment)
Take a screenshot of your computer while it is displaying your
color,
based on your birthdate, and submit it. (On Windows machines,
press
PrintScreen, then open Paint and click Paste. Then click Save
As and
name your file. On Macs, press Command-Shift-3. The
screenshot is
added to your desktop.)
9.3
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Oscilloscope image for Lab 8
Each small tick mark along the x axis represents 5.0 x 10-9 sec,
or 5.0 nanoseconds, or
0.0000000050 sec.
35. macaulay.cuny.edu
Kent State University
Act IV
Lab 12
Exploring refraction in lenses
The idea: Light is the fastest-moving phenomenon in the
universe, but ordinary
stuff – air, water, glass – slows it down appreciably. If light
moves from
one medium to another ‘head-on,’ so to speak, it slows down
but it
continues in the same direction. But if light enters a new
medium at an
angle, its direction of motion changes along with its speed.
That fact,
alone, makes possible our ability to bring light to a focus, to use
and
control beams of light for practical purposes and for
entertainment, and
to see! The great gift of eyesight depends completely on light
slowing
and bending in denser media.
But how does light ‘know’ how much to bend? Think about
three light
rays, as in the simple diagram at the left, scattering off the tip
of the
object, an arrow standing upright. (Why do physics books
always use
arrows as objects? How often do you take a picture of an arrow
standing
36. on its tail?) Of course there are uncountable numbers of rays
coming
from the arrow tip, and every other point along it – as well as
everything
else! How does a simple, inanimate curved piece of glass sort
them all
out into an image? How does your eye do it?
But back to those three rays. What happens to them, happens to
all.
One explanation of why they come to a focus is that the farther
the ray
strikes the lens from the center, the more obliquely it hits the
surface,
and the more strongly it bends. The red ray hits the surface at a
pretty
large angle, but it comes out at the exact same angle, and so the
effects
cancel for it and it passes straight through. The blue ray makes
a smaller
angle with the surface coming in, but a larger one going out,
and so it is
bent downward quite a bit. The purple ray makes the most
glancing
impact of all with the lens surface, so it bends the most. In
short, rays
that hit the lens farthest from the center bend the most, and they
‘need’
to bend the most to come together.
A deeper explanation came from French mathematician Pierre
Fermat.
In 1662 he suggested that light always takes the least time – not
the
37. shortest path, but the quickest! The red ray takes the most
direct route
of the three, but it goes through the thickest part of the lens and
slows
down the most. The purple ray obviously takes the most
roundabout
path, but it passes through the least amount of glass and so is
‘penalized’
the least. The trouble is, Fermat’s Principle of least time seems
to
suggest that light ‘knows’ ahead of time where it will end up,
and then
calculates, somehow, the quickest path.
The best explanation comes from redefining distance. If we
measure the
path length of those three rays in human terms, using
millimeters or
inches, then the paths are of different length. But how does
light
measure distance? In terms of wavelengths! Because the
frequency of
light (its color) does not change in refraction, but the speed
does
change, the wavelength of light changes. All three rays in the
diagram travel the same number of wavelengths, so the rays
interfere constructively only at exactly one point. The red ray
travels through the most glass, so its wavelength stays shorter
for more
cycles. The purple ray travels through the least glass, so it has
relatively
few short waves. The point where all the rays meet is the only
point
where all three rays arrive in step, in the same phase
relationship as
when they left the arrow tip. They all left together; they must
38. all arrive
together if they are to form an image!
The same wonder is at work when you read these letters. Light
streaming off your computer monitor, or bouncing off these
letters on a
page, go off at the same instant, and almost as if the waves are
holding
hands, they arrive together at a point inside your eye. Try to
keep that
sense of wonder about everything you ever see! – even the
mundane
images in this experiment.
What you’ll learn: By the end of this lab, you will understand
how to
1) measure the focal length of a convex or converging lens,
2) predict where images form when refracted by a convex lens,
and
3) explain why object distance and image distance are inversely
related.
What you’ll need: Lens from any reading glasses
Yard stick or tape measure from your lab packet
Scissors
Transparent tape
Index card from your lab packet
Computer monitor to act as a light source
Dark room
Willing assistant
What you’ll do: 1) Acquire a pair of simple, non-prescription
reading glasses. Since you
39. won’t be harming them, you could just borrow a pair from most
any
older person you know. Or you could buy an inexpensive pair
from a
drug store or discount store. You might do especially well at
dollar
stores, or Goodwill. If you get a new pair with the power
marked in
diopters (such as +2.0) so much the better.
2) Next, make your own meter stick by cutting apart the strips
printed
on the card stock in your lab packet. Lay them accurately end
to end
and tape them together to make a flexible and temporary but
accurate
way to measure. You have enough strips to make a second one,
as well,
if you need it.
3) Now, measure the focal length of the lens. As illustrated in
the
introductory video, use a room that can be darkened well by
closing
doors and pulling shades. You may have to do the lab at night
with the
lights off, if you can’t darken the room enough by day. Bring
along your
assistant and your laptop to use as a light source.
(If you use a desktop computer in a room that can’t be darkened
well, as
I do, then choose some other small light source – a flashlight, a
candle, a
small desk lamp – anything that is bright if you look at it, but
that does
40. not pour a lot of light all over the room.)
Turn up the brightness of your laptop as high as you can and get
a large,
high contrast image in your screen. In the introductory video I
down-
loaded a fat red arrow and enlarged it so it nearly filled the
screen on a
bright white background. Or, you could open a blank white
word
processor screen and type I LOVE PHYSICS, or maybe
something else,
in giant bold letters.
Set the laptop on one end of a long table or counter, if you have
one. If
not, use the floor! Put your hand over one lens of the glasses,
so that
only one lens is clear and available for use. Hold the lens
several feet
away from the laptop screen; the biggest problem in this lab is
starting
with the lens too close to the laptop! Have your assistant hold
the card
several feet beyond the lens, as I demonstrated in the
introductory
video. Then slowly move the lens toward or away from the card
until
you can see an image of the laptop on the card. It won’t be a
perfect
photographic image, but it still should be pretty clear and
recognizable.
What kind of image is it, virtual or real? How do you know?
Record
your answers on the Report Sheet.
41. 4) With the lens in place and the image in focus on the card,
have your
trusty assistant measure, as accurately as possible, the distances
from
both sides of the lens, in centimeters. The distance from the
lens to the
laptop is the object distance, do. On the other side of the lens,
the
distance from the lens to the card is the image distance, di.
Record
both distances on the Report Sheet.
5) While you have everything more or less in place, repeat the
process
twice more. Have your assistant move the card farther away
from the
laptop or closer to it – but not very close! – and again move the
lens back
and forth until you see a reasonably clear image. Again,
measure do and
di for each of the two new trials and record them on the Report
Sheet.
6) You can get up off the floor and turn the lights back on!
Next, use
the lens equation to solve for f, the focal length of the lens,
from each of
the three pairs of distances. That equation is:
1/f = 1/do + 1/di
All three variables of interest are in the denominator; this is not
the
same as f = do + di!
42. You can use the equation as written, but here it is, solved for f:
f = (do di) / (do + di)
That is, the focal length of lens equals the product of the two
distances
divided by their sum.
Calculate the focal length of the lens from each pair of numbers
and
round them to whole numbers. Record your results in the third
column
on the Report Sheet.
7) Zoom lenses on cameras can change their focal length, but
one solid
piece of glass or plastic, as you had in your hands, has one
fixed focal
length, so all of the focal length values should be more or less
the same.
(If so, good for you! If not, back into the dark to do them
over!)
Average out the three values of the focal length and again round
it to a
whole number.
8) The shorter the focal length of a lens, the more strongly it
will
magnify an image if you hold it close to, say, small print on
paper.
That’s seems backwards, in a way, that a smaller focal length
would have
a higher magnifying power, so opticians and reading glass
makers
43. invented the diopter scale. By definition, the power of a lens in
diopters is the reciprocal of its focal length, in meters. So, a
+2.0 lens
would have a focal length of 1/2.0 or ½ m. Since we are
working in
centimeters, we can say that the diopter power is 100 cm
divided by
the focal length in cm. Using the value from step 7, calculate
the
diopter power of your lens. Round it to the nearest 0.25. How
does that
compare with the manufacturer’s stated diopter value, if known?
As a brief aside, why is the image not perfectly clear, when
these are
reading glasses, after all? It’s because when you are reading
through
them, you are using only the tiny part of the lens directly
between your
eye and the letters you are trying to read at any one time. But
in this
experiment, you are using the entire lens, all at once. It’s easy
to make a
lens that is accurate over a small portion of its surface, and
much harder
– and so, much more expensive – to make it accurate over the
entire
surface. That’s why inexpensive, one-time use cameras, like
those left
on the table for you at wedding receptions, always have small
lenses and
must use flash for most pictures. Expensive cameras have large
diameter
lenses which often cost more than the camera itself!
44. Web extension
The f/ ratio or f/ number for camera lenses is defined as the
focal length
of the lens divided by its aperture, or diameter. What are some
of the
more-or-less standard values of f/ ratios? With each increase in
f/
number, what happens to the brightness of light passing through
the
lens?
Be sure to include the web address of your sources.
Kent State University
Act III
Lab 9
Lab 9
Exploring polarization
Report sheet
Name
Objective: To 1) detect the polarization direction of light,
2) determine which kinds of objects look different when viewed
through
a polarizer, and
3) produce color using crossed polarizers.
45. Data:
Which way was your slide oriented when you drew the vertical
line on its frame?
Which way is the display on your computer oriented?
List items or scenes you examined through your polarizer, and
what you observed:
9.1
List some items that you held between your monitor screen and
your polarizer that
produced interesting effects.
Web extension
What are some animals that can discern polarized light?
For any one of those animals, how does its ability to detect
polarized
light serve that species?
Sources you consulted:
PR Photo (Proof you Really did the experiment)
Submit a photo that a friend took of you, looking through your
polarizer
at a piece of plastic in front of your monitor.
9.2
46. MyTextField: Group1: OffTextField__1610823267834:
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macaulay.cuny.edu
Kent State University
Act III
Lab 10
Exploring color addition and
subtraction
The idea: You know from the companion course that color is
truly in our own
brains. Objects don’t have color, and neither does light. Light
has only
different frequencies or wavelengths, and objects have only
traps that
catch one frequency or another and scatter the rest. Our eyes
and brains
are tickled differently by each frequency, and in response our
brains
paint a particular color in that speck of our visual field. The
whole world
is a giant paint-by-number kit, and instead of little color codes
printed
on the canvas, we receive little frequency codes in the colorless
light we
see.
47. Only three frequencies of light are necessary to generate the
illusion of
all others – those that tickle our eyes in ways that we have
learned to call
particular shades of red, green, and blue. That’s all that
televisions and
computer monitors can ever generate, but they can make more
than 16
million different colors from them!
What you’ll learn: By the end of this lab you will understand
1) how additive and subtractive primary colors are related,
2) how televisions, computer monitors, and stage lights create
colors by
combining primary colors, and
3) the colors needed to generate any particular composite color.
What you’ll need: Computer with internet connection
What you’ll do: 1) With any browser of your choice, go to
www.michaelbach.de/ot/col_mix
and you will see an interesting and well-designed color
simulator.
10.1
Click fullscreen and then at the lower left, click preview, pull
down the
menu, and click white, giving you total control of the program.
2) First, an easy exercise. Turn any two sliders up all the way,
48. while the
third is off. Name on the Report Sheet the color that you see.
Repeat
the process until you have seen all three combinations of two
colors
each. Remember that the colors you see are illusions, painted
by your
brain as your eyes are tickled by two frequencies at once. All
you ever
see on the screen is red, green, or blue in various intensities.
Use this color wheel for the next part of the lab.
3) Let’s number the color swatches, as the hours on a clock.
So, yellow
is number 1, violet is number 6, and yellow-green is number 12.
For each swatch, adjust the color sliders on the computer so that
the
window on the screen matches each color as well as possible.
You
should see an easy pattern! Write on the Report Sheet the slider
settings
for each color that give the best match. The sliders are not
numbered,
but you can number then in your imagination from zero at the
bottom
of each slider up to 5.
4) Next, make “your color,” based on your birth date, as
described
below.
www.urlnextdoor.com
10.2
49. Red – take the month number of your birth (for example, 3 for
March or
9 for September) and multiply it by 0.41, to scale the month
numbers
out along the range of intensities. Record that number on the
Report
Sheet and set the red slider to that number. You will of course
have to
estimate the slider setting, since we are supposing that it
indicates whole
numbers starting from zero.
Green – take the date of your birth during the month (for
example, the
15 or the 22 ) and multiply it by 0.16. Record that number and
set theth nd
green slider to its value, again estimating as well as you can the
slider
setting that seems closest to the number you calculated.
Blue – take the day of the week on which you were born, with
Sunday
equal to 1 and Saturday, 7. Multiply that number by 0.71,
record it, and
set the blue slider to it.
(What? You don’t know what day of the week you were born?
Go to
http://www.timeanddate.com/calendar/generate.html
Enter the year and the country in which you were born, and then
scroll
50. down the calendar to see which day of the week matches your
birth
date.)
You will see a color swatch that is unique to that day, one of
more than
2500 possibilities. Think of it as your own personal color!
Save it and
post it on the Report Sheet. If you are using a PC, press
PrintScreen to
capture the screen to the Clipboard, and use any photo editing
program
to crop out everything but the color swatch in the black circle.
Are you
a Mac user? Then press Command-Shift-3 to automatically save
a PNG
file on your desktop. Use any photo program to crop out
everything but
the color swatch in the black circle.
Describe the color as well as you can on the Report Sheet.
Please remember that your color, as all of the colors produced
in this
lab, is an illusion from your eyes and brains. The color that you
think
you saw never really existed at all; it was simply the averaged
signal from
your eyes to your brain. Wow!
5) Now experiment a bit with color subtraction, as well. Set the
spotlights to produce each of the colors indicated in the table on
the
10.3
51. Report Sheet, and then insert the color filters by moving each
slider all
the way up. Record each result on the Report Sheet. Yes, there
are
many entries, but they go quickly, and the resulting table will
be a great
help for the homework and quiz in the lecture course!
6) Want more practice? Find a Post-it note, or an index card
and a piece
of tape, and use it to cover the right side of the screen, flush
with the
yellow filter, as shown on the next page, so that it hides the
final color.
Post-it note or index card
here to cover the final
color swatch.
7) Click auto run and watch as the spotlights and filters change
randomly. Whenever you feel like it, click stop, then consider
the color
of the light coming in to the set of filters and what each filter is
removing. Make your best guess of the final color, then lift the
Post-it
note or index card to peek and see if you were correct. You
don’t need
to record any of these results; this is just a suggestion for more
practice.
I hope that you will never think of color in quite the same way
again!
Web extension
52. All television sets and computer monitors can only produce red,
green,
and blue – until now. Why did Sharp add a fourth color,
yellow, on their
Quattro line of flat-screen televisions?
Be sure to include the basic web address where you found your
answer.
10.4
Transcript: PHY 21041 Lab 9
Like my new glasses? You might recognize them as IMAX 3D
movie glasses. It turns out,
3D movies are one of the most important applications of polariz
ed light in
entertainment and the arts. They act like gate keepers. They m
ake sure that light
coming from the screen that’s meant for my left eye only gets in
my left eye, and light
meant for my right eye only gets in on that side. The little pola
rizer we supplied in the
kit for the class, is a lot like this, but it’s more of a monocle! O
h I say.
The first thing we have to do, is figure out the polarization dire
ctor in your filter. We’ll
do that out in the hall. Light can be polarized by reflecting off
a smooth surface. So find
a smooth hallway, a smooth, polished hallway, and take a look a
long the floor at about a
53. 45 degree angle from your point of view. Hold the polarizer up
close to your eye, and
rotate it, and watch some of the reflections‐not all‐ but some of
the reflections go away.
Then you want to make a mark on the frame of the polarizer ver
tically. Because that
means you found the vertical orientation that blocks the horizon
tally polarized light
coming off the floor.
Let’s take a look in the camera and show you what this would lo
ok like. We’re going to
put the polarizer in front of the camera lens and rotate it. I hop
e you see that some of
those reflections went dark.
It turns out that most flat screen displays work because of polari
zed light, as you will see
in the course. When I hold the polarizer in front of the laptop,
you can see that I can
allow the light from the screen to pass through or not to pass thr
ough. I can block the
light by turning the polarizer about 45 degrees. Explore your o
wn environment, looking
for things that look different through the polarizer in your kit.
We zoomed in tight on my computer screen. This is a source of
polarized light. We
humans, can’t detect polarized light directly. But Keith is now
going to hold the
polarizer in front of the camera, and rotate it to make the screen
go dark. We now have
cross polarizers‐ virtually no light is getting through. But amaz
ingly, if I hold some
plastic objects in place, your able to rotate the plane of polarize
54. d light different colors
are rotated by different amounts. And you can see amazing colo
rs in this hard, plastic
fork or in this hard plastic tape container. If you happen to hav
e Karo syrup‐ corn syrup
around, that also gives a fantastic view. The glucose molecules
in there are able to
rotate polarized light and the thickness of the syrup because it’s
a curved bottle
determines what color will be rotated to come through.
I hope you have fun with polarized light in this lab.
macaulay.cuny.edu
Kent State University
Act III
Lab 9
Lab 9
Exploring polarized light
The idea: If you have not yet watched and listened to the
narrated PowerPoint
presentations “Wave properties of light - part 3" and “A little
on liquid
crystal displays,” please go to the companion course page in
Learn and
study them.
By now you know that we humans can see only the tiniest slice
55. of all the
light waves out there. Not only that, we are unable to detect the
direction in which the changing electric fields of light oscillate
– that is,
we can’t detect polarization of light. But with just a little help
and a flat-
screen computer monitor, we can explore this otherwise hidden
and
unknown aspect of light. The results can be surprising and
beautiful!
Remember that a polarizer – a thin plastic film in a cardboard
frame, in
this case – is a sort of gatekeeper, like a bouncer in an exclusive
club.
Just as some people with certain characteristics are let in to the
club and
others are kept out, the polarizer allows light vibrating in one
plane to
get through. The difference with the bouncer analogy is that
people
who don’t make the cut are simply turned away at the door, but
a
polarizer absorbs and completely annihilates light that doesn’t
get
through! It’s risky business getting in to the Polarizer Club!
What you’ll learn: By the end of this lab you will understand
1) how to detect the polarization direction of light,
2) which kinds of objects look different when viewed through a
polarizer, and
3) how to produce color using crossed polarizers.
9.1
56. What you’ll need: Flat-screen computer monitor
Polarizer from the lab packet
Pencil or pen
A few pieces of hard clear plastic from
around your home or dorm room
What you’ll do: 1) First, you need to determine the orientation
of the polarizer in your
packet. The film is in a rather plain cardboard frame with no
indication
of the vibration direction that will be blocked.
Find a smooth, shiny hallway with multiple ceiling lights.
Office
building, school building, and dorm hallways are great. (In a
pinch, you
could use something as simple as a glass of water positioned so
that an
overhead light reflects up off the water to your eyes at about a
45o
angle.)
Look down the hallway at the series of reflections of the ceiling
lights off
the floor. Choose a reflection about six feet or so in front of
you. Close
one eye and hold the polarizer close to your open eye, looking
through it
at the reflection ahead of you. Slowly rotate the polarizer left
or right as
you continue looking through it, until the reflection seems to
disappear,
mostly or even completely. One edge or another of the frame
57. will be
parallel to the floor; the polarizer should not be diagonal or
askew.
Use a pencil or pen to make a vertical line, perpendicular to the
floor,
on the edge of your polarizer frame. The light bouncing off the
floor is
polarized horizontally, parallel with the floor. That is, light
with its
electric field component parallel with the floor will skip off the
surface
and bounce up, but light with its field oscillating vertically will
take a
dive into the floor polish and be absorbed. The line you draw
on the
polarizer frame indicates the vibration direction of the light that
makes
it through; drawing the line vertically when the reflected light is
extinguished shows that the orientation of the polarizer is
opposite that
of the reflected light. Record on the Report Sheet the direction
of the
line you drew.
2) Now use one eye again to look through your polarizer at
your
computer monitor. Slowly rotate the polarizer right or left and
you are
likely to see an amazing sight – light from your monitor will be
blocked
or cancelled with one orientation of the polarizer. That’s
because liquid
crystal displays produce polarized light, and when the line on
your
polarizer is perpendicular to the oscillation direction of the
58. light from
your monitor, light can’t get through. You may find that the
light from
9.2
your monitor is polarized vertically, or horizontally, or
diagonally. (I
have two Dell monitors on my office desk, but one produces
vertically
polarized light while the other emits diagonal light. My guess
is that
Dell buys display components from various manufacturers, and
I
happened to get two slightly different models with screens made
by two
different companies.) Record your observation on the Report
Sheet.
3) Try other displays around where you live – big screen
televisions,
calculators, the grey reflective displays on some land-line
phones and
microwave ovens, or perhaps on some car radios. Record what
you
looked at, and what you observed, if anything. (A negative
result is still
a result!)
Also, try looking at patches of blue sky at various angles from
the sun, or
at reflections off smooth surfaces. Record what you discovered.
4) Finally, have fun with color. Gather up a few clear plastic
59. items. The
hard styrene plastic in clear plastic tableware is excellent, as is
an
inexpensive school ruler or protractor, or the dispenser that
holds a roll
of ‘Scotch’ tape. Try a Zip-loc type bag or even the cellophane
from a
cigarette package.
Open a blank word processor document on your computer so
that your
screen is mostly blank white space. Look through your
polarizer and
rotate it to extinguish the light from your monitor. The hold
any of
those plastic items in the space between your monitor and your
polarizer. You will probably see stunning displays of color
from what
looks like dull, transparent plastic. Some kinds of organic
molecules, as
in styrene and some other plastics, can rotate the plane of
polarized
light, in the same kind of way that your body rotates on a spiral
staircase. Different frequencies of light rotate different
amounts, and
the color you see is the frequency that rotated 90o and made it
through
your polarizer.
List on the Report Sheet some items that looked especially
interesting.
9.3
60. Web extension
Even though we humans can’t detect polarized light, many
animals can. Do
a quick search on the internet to find some that can detect
polarized light.
For any one of them, explain briefly why the ability to discern
polarized
light serves an important function for that species.
Be sure to include the web address of the site where you found
the
information.
9.4
Kent State University
Act IV
Lab 11
Exploring reflections
Report sheet
Name
Objective: To 1) discriminate real images from virtual images,
2) learn more about geometrical optics with flat mirrors, and
3) observe real images from a concave reflecting surface.
61. Data:
Distance between the Post-It notes on the mirror (that is, the
height ot Flat Albert’s
image) in cm:
Flat Albert’s actual height, in cm
How does Albert’s apparent height in the mirror compare with
his actual height?
What happened to the fit between Albert’s image and the marks
on the mirror as you
moved back and forth from the mirror?
11.1
Briefly describe your image in the back of a spoon:
Is that image virtual or real? How do you know?
Briefly describe your image in the bowl or front of a spoon:
Is that image virtual or real? How do you know?
Web extension
Why do catadioptric or Cassegranian telescopes use both
concave and
convex mirrors?
Sources you consulted:
62. PR Photo (Proof you Really did the experiment)
Submit a picture with you looking through Flat Albert.
11.2
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macaulay.cuny.edu
Kent State University
Act IV
Lab 11
Exploring reflections
The idea: You see reflections in mirrors so often that you
probably think you
understand them. And you probably do – up to a point. But
there are
some interesting consequences and complications that you will
explore
in this fun and easy lab.
What you’ll learn: By the end of this lab you will understand
1) how to discriminate real images from virtual images,
2) more about geometrical optics with flat mirrors, and
63. 3) how real images are formed from concave reflecting surfaces.
What you’ll need: Post-It notes or a roll of masking tape
Ruler
Scissors or X-Acto knife
Flat Albert image from the lab packet
Wall mirror
Large, shiny spoon
Willing assistant
What you’ll do: 1) Use scissors or an X-Acto type knife to cut
an eye hole in the cartoon
image of Albert Einstein in your lab packet.
2) Grab some Post-It notes and a friend and go to a room with a
normal-sized wall-mounted mirror. Any bedroom or bathroom
mirror
will d0. Give the Post-its to your friend to hold.
3) Stand about six feet or so away from the mirror, hold the
Einstein
image in front of your face, and with one eye look through the
eye hole
so that you see his cartoon image in the mirror. Ask your friend
to stick
a Post-It note on the mirror where you say to put it, so that it
looks to
11.1
64. you like Einstein is standing on the note. It’s fun to watch this,
as
people will almost always assume you will tell them to stick the
note
down low on the mirror. In fact, the note will have to move up
surprisingly high. Give the person directions, such as “A little
higher,
over to the left,” and so on, until it looks to you that Flat Albert
is
standing right on the note.
Do the same with another Post-It note on the mirror so that it
seems to
be resting right on top of Flat Albert’s head, as if the two notes
were
clamps that were holding him in place.
4) Use a ruler to measure the distance between the Post-Its on
the
mirror. It’s always better in physics to use centimeters! Record
that
distance, which is the height of Albert’s image, on the Report
Sheet.
5) Now use the ruler again to measure on the piece of cardstock
the
actual height of Flat Albert, from his toes to the top of his
pointy hair.
Record his height on the Report Sheet as well.
How do those last two measurements compare – Flat Albert’s
actual
height, and the distance between the Post-It notes on the mirror?
Record your observation on the Report Sheet.
6) Go back to where you were standing and look through
65. Albert’s eye
hole again. Take a few steps forward and backward, as far as
you can
move in the room, and observe Albert’s image and the Post-Its
on the
mirror. As you move, does Albert still fit between the notes?
Record
your observation on the Report Sheet.
What do you conclude, in general, about the size of a mirror
needed to
see your whole self? Record your conclusion on the Report
Sheet.
Most everyone, in my experience, assumes that the size of the
mirror
you need to see your whole self depends on your distance from
the
mirror. That misconception stems from the fact that we are not
two-
dimensional objects, and that our eyes are in front of the front-
to back
midline of our bodies.
If you look at yourself very closely, as in a small mirror in a
compact, you
see only a small part of yourself. If you pull it back to arm’s
length, you
will see quite a bit more of yourself. But if someone held the
mirror for
you and you backed up to two arm-lengths away, the amount of
yourself
11.2
66. you could see would hardly change at all. This is another
example of
where our routine experience fails us if we apply that
experience to more
extreme circumstances.
7) You notice, of course that as you look at yourself in a
mirror, you are
right side up. That means that your image is virtual. It may or
may not
be virtuous; that’s not for me to say! But seriously, a virtual
image is
one that cannot be projected onto a screen or surface, and it
depends on
one’s point of view. After all, while you were looking at
yourself in the
mirror, you had to direct your assistant where to move to place
the
notes, because he or she could not see that same image that you
did. A
virtual image is not on the mirror, but appears to be behind it.
We can explore virtual images further and their opposite, real
images,
using something as simple and common as a spoon. (I hope that
you
have noticed this on your own way before this.) Real images
are always
inverted and can be projected.
Look at yourself in the back of a shiny spoon. Write a few
words on the
Report Sheet to describe your image, and whether it is virtual or
real.
67. 8) Now flip the spoon over and look its bowl. Describe briefly
on the
Report Sheet what you notice about that image when you look
into the
bowl of a spoon. Is it virtual or real?
Web extension
Look up information on the web about Cassegranian or
catadioptric
telescopes – both terms mean approximately the same thing.
Tell me
how they use both concave and convex mirrors.
Be sure to include the basic web addresses where you found
your
answers.
11.3
Kent State University
Act IV
Lab 12
Exploring refraction in lenses
Report sheet
Name
68. Objective: To 1) measure the focal length of a convex or
converging lens,
2) predict where images form when refracted by a convex lens,
and
3) explain why object distance and image distance are inversely
related.
Data:
Diopter value (power) of the reading glasses, if known:
Is the image the laptop or other light source virtual or real?
How do you know?
Object distance
(do), cm
Image distance
(di), cm
Calculated
focal length (f),
cm
Average
Power of your lens, in diopters :
If you knew the power of the lens when you obtained the
glasses, how well does your
calculation of the power agree with the manufacturer’s value?
Web extension
69. What are the more-or-less standard values of f/ ratios? With
each
increase in f/ number, what happens to the brightness of light
passing
through the lens?
Sources you consulted:
PR Photo (Proof you Really did the experiment)
Upload a photo (use of flash will probably be necessary, unless
you have
good camera) of you holding the lens in position in front of the
laptop or
other light source that you used.
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TextField__1469601251388: TextField__1469604128040:
TextField__1469607752239: TextField__1469610459884:
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MyMultiLineTextField: TextField__1470244751818:
Transcript: PHY 21041 Lab 10
Hi! Suppose you could take a look at your computer monitor clo
se up. I mean, really
close up! What would you see?
Wherever you looked, you would see these little bricks of color,
70. little micro‐Legos
stacked in row after row. But no matter where on the screen yo
u looked, you would
only see these three colors –
a particular sort of satanic red, a bright Kelly green, and a
deep, deep blue. That’s it! That’s all the colors we have. Ever
ything you see on your
monitor, phone, or color TV is just combinations of those colors
. In today’s lab you will
explore this further by taking control of one big pixel.
Here it is, under this fancy light shield, um, and upside down ca
rdboard box. College
may be expensive, but it’s not because we spend more than we n
eed to o equipment.
Inside, you see the light bulb, which it spread the light and the c
amera staring at the
bulb to show the color of light we make. Let me move the came
ra and the light bulb.
Now you can see nine special light‐emitting diodes, or LEDS.
What’s special about them
is that each contains three separate color generators. By adjusti
ng the computer
controls, I can energize just the red elements, or the green, or th
e blue. Notice how
similar those colors are to the standard primary colors you saw
a moment ago. Let me
put all of this back together so we can use it.
This is another of the remote‐access labs in our course where yo
u take control of the
equipment from wherever you are. It’s a simple–
looking program, but it does a lot of
work. You have three sliders, one for each primary color. And
the box shows the color
71. that the camera sees the color that you have made. What’s amaz
ing is that it is all an
illusion!
You see, the LEDs that you just saw inside the box are either fu
lly on, or completely off.
Each slider determines the fraction of the time that each LED se
gment is turned on. If
all three are on any value but zero, then they all turn on fully br
ight. They stay on for
the time that you set and then turn off in the order of increasing
settings. The whole
cycle repeats 120 times a second. If you had super‐fast Spidey
senses, you would see
white at first as all the colors are present, then a combination of
two colors, then just
one, and then darkness, and then start all over again! Our amazi
ng brains merge all of
that action into smooth, continuous motion, and we see shades o
f each color, blended
into one color! With all the hundred different timing settings for
each color, you can
make one million colors! Let’s try them all, one at a time! No,
let’s not, but you can try
a few in this fun and easy lab.
Transcript: PHY 21041 Lab 12
For this lab, you need to do a little bit of work ahead of time. Y
ou need a pair of glasses,
like old people would wear. Not prescription glasses, not bifoc
als‐ they wouldn’t work,
just ordinary, plain vanilla reading glasses. If you’re too embar
72. rassed to borrow them
from somebody, just go to Goodwill or something like that to ge
t the cheapest reading
glasses you can find. So go ahead and get some glasses and co
me right back!
Unidentified voice: Hey, you young whippersnapper! Come bac
k here with my glasses!
And get off my lawn!
Unidentified voice: Sorry, he made me do it! I’ll be right back.
Unidentified voice: Here you go! Gotta run!
Oh, Thank you! I guess.
Now all we need is a place to set this up. We need a really dark
room. I wonder where
we could find one of those. Well, this is convenient. Let’s go o
n in.
We found our dark room, now. Here are the glasses my student
just got for me. And
I’m using my laptop as a light source. I found a big, red arrow t
here as an image that we
can use. I’m going to set it right here at the end of this long tab
le, with the screen
straight up and down. Way down there, at the other end of the t
able, I have the piece
of index card that came from your packet. I have it attached to
your book end down
there. I have another book end right here that I can use to stead
y the lens so the image
will be sharp and clear when I move it down there.
Let’s see what you would do now in the lab. I’m going to hold t
he glasses, covering one
73. lens. Only one lens is being used. I’m going to start a long dist
ance away from the
computer screen. The most common problem is in doing this la
b is starting too close.
So start a good distance away from the computer screen. And w
hat I’m going to do now
is move the lens further and further away until I see an image co
me to focus on my card
over here. And there it comes, we’re almost there. And there is
a nice sharp image in
the card. You’ll need to then measure, this distance from the le
ns to the computer,
that’s called the object distance, DO, because the computer scre
en is the object. We’ll
also measure from the lens to the card. That’s the image distanc
e, DI.
From the instructions in Blackboard learn, you’ll see how to cal
culate the focal length of
this lens using DO and DI. What I want you to do is several dif
ferent trials like this,
where you will move the cardboard screen and then move the le
ns to a new place to
refocus again, in each case measuring DO and DI.