This document provides instructions for an experiment to:
1. Create a natural polarizer using salol crystals between microscope slides and observe it under a microscope. Salol crystals polarize light by selectively absorbing the oscillating electric field oriented in one direction.
2. Investigate how the intensity of light passing through two consecutive polarizers is affected by rotating one relative to the other. The intensity is highest when they are aligned and lowest when they are crossed.
3. Relate the results to Malus's Law, which states that the intensity of light (I) is equal to the original intensity (I0) multiplied by the cosine squared of the angle between the polarizers.
Here are the slides describing talents and hedgehog concepts in the context of students' future careers. It's the background to our final assignment for the semester: http://openwetware.org/wiki/User:Steven_J._Koch/Talents_assignment
Most of the times this study confused me...so, i just put some important points in one place to easily keep them in mind..hope it will help other students as well..and inform me, if a reader find anything new to improve it further.
Here are the slides describing talents and hedgehog concepts in the context of students' future careers. It's the background to our final assignment for the semester: http://openwetware.org/wiki/User:Steven_J._Koch/Talents_assignment
Most of the times this study confused me...so, i just put some important points in one place to easily keep them in mind..hope it will help other students as well..and inform me, if a reader find anything new to improve it further.
This guide is intended to assist those who seek to capture images of the
eye, using the slit lamp, to improve the quality of their photography by using
simple-to-follow illumination diagrams and high quality image examples.
We hope this book provides inspiration and motivation to anyone who is
involved in the art of documenting the unique properties and pathologies of
the eye and through Haag-Streit we offer a number of instruments to help
you.
Characterization methods - Nanoscience and nanotechnologiesNANOYOU
An introduction to characterization methods.
This chapter is part of the NANOYOU training kit for teachers.
For more resources on nanotechnologies visit: www.nanoyou.eu
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 ...
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.
This guide is intended to assist those who seek to capture images of the
eye, using the slit lamp, to improve the quality of their photography by using
simple-to-follow illumination diagrams and high quality image examples.
We hope this book provides inspiration and motivation to anyone who is
involved in the art of documenting the unique properties and pathologies of
the eye and through Haag-Streit we offer a number of instruments to help
you.
Characterization methods - Nanoscience and nanotechnologiesNANOYOU
An introduction to characterization methods.
This chapter is part of the NANOYOU training kit for teachers.
For more resources on nanotechnologies visit: www.nanoyou.eu
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 ...
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.
1. Developing Questioning Skills
The Big Question: Can you make your own polarizer of light? How do two
consecutive polaroids behave?
Starter:
Electromagnetic radiation consist of electric and magnetic fields that oscillate at
right angles to one another. The changing magnetic field produces the changing
electric field and the changing electric field produces the magnetic field!
However the electric field can be rotated about a central axis:
What does the polarizer do to the light?
How does it achieve this?
In your experiment you will aim to make a natural polarizer and view it under a
microscope. Then you will aim to investigate what happens when you rotate
two polarisers together.
2. Practical Instructions
1. Heat the salol crystals in the test tube until they have just melted.
2. Using the dropping pipette take one drop of the molten salol and place it
between the two microscope slides.
3. Place the microscope slide under the microscope fully illuminated and try
and get the crystals in focus.
At this point the light arriving from the light source to your eye will be
polarized.
Use the ideas covered in the starter to explain why the salol acts as a
polariser:
(HINT: what have the crystals done to the light?)
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4. Now get another polarizer. Rotate it through the following angles (you
will need to make sure your crystals are aligned at 0 degrees). Record the
brightness of the light and estimate what fraction of the original light
passing through the crystals you are ‘seeing’.
Angle/degrees Fraction of original light intensity
0
45
90
135
180
If you can’t do this exactly try doing it with two ‘normal’ polarisers.
When is the light intensity maximum?
When is the light intensity minimum?
3. Which of the following graphs explains the action of two polarisers
rotated relative to one another?
Intensity of
light
Intensity of
light
Malus’s Law for two consecutive polarisers states:
I = I0 cos2
Explain what the symbols in the equation mean and how this relates to
your experiment.
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