0
Upcoming SlideShare
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Standard text messaging rates apply

# Science8 Unit C Lightand Optics Lesson5 The Wave Modelof Light

2,569

Published on

EMR …

EMR
Microwaves
UV waves
Infrared Waves
X-Rays
Gamma Rays

1 Comment
2 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
Your message goes here
Views
Total Views
2,569
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
114
1
Likes
2
Embeds 0
No embeds

No notes for slide
• ### Transcript

• 1. Light is part of the electromagnetic spectrum and travels in waves
• 2.
• Lesson #5, Section 3.1-3.2. Pages 212-220
• Learner Outcomes
• I can describe the characteristics and composition of sunlight
• I can explain the wave properties of light and the electromagnetic spectrum
• I can describe some of the technological applications of electromagnetic spectrum radiation
• I can recognize the dangers associated with certain forms of radiation
• 3.
• Waves and light have two big similarities
• Both are forms of energy
• Both travel out in all directions
• The Wave Model:
• Different colours of light have different wavelengths
• Waves with shorter wavelengths have higher energy than those with longer wavelengths
• 4. The high parts of the wave are called crests
• 5. The low parts of the wave are called troughs
• 6. The distance from crest to crest is called wavelength (the distance from one complete crest and one complete trough)
• 7. The height of the crest or the depth of the trough from rest position is called the amplitude
• 8. The Frequency is the rate at which the crest and the trough move up and down. The number of cycles in a period of time - which is usually measured in hertz , or cycles per second.
• 9.
• Different colors on the electromagnetic spectrum have different wavelengths ( nanometers ) and different frequencies ( hertz ).
• 10.
• 11.
• 12.
• 13.
• 14.
• 15.
• ROY-G-BIV
• 16.
• ... describe the characteristics and composition of sunlight?
• ... explain the wave properties of light and the electromagnetic spectrum?
• 17.
• #1. What properties do light and the waves in your bath water share?
• ______________________________________________________________________________________
• #2. Draw a diagram of a wave with an amplitude of 4 cm and a wavelength of 10 cm
• 18.
• The sun is the most abundant source of direct natural light on the Earth.
• The tiny band of visible light that we see is only part of the entire spectrum of light energy we receive.
• The light waves, electrical and magnetic fields vibrate as they radiate to earth.
• 19.
• Radiation is a natural part of our environment.
• Natural radiation reaches earth from outer space and continuously radiates from the rocks, soil, and water on the earth.
• Background radiation is that which is naturally and inevitably present in our environment. Levels of this can vary greatly.
• Radiation is energy traveling through space. Sunshine is one of the most familiar forms of radiation.
• Sunshine consists of radiation in a range of wavelengths from long-wave infrared to shorter wavelength ultraviolet .
• 20.
• Ra dio D etection a nd R anging
• 21.
• Radio waves are around us all the time.
• Radio waves have a longer wavelength and a lower frequency than visible light.
• Different types of radio waves have different uses.
• Signals from radio and television stations , cell phones and even distant stars pass through your body every day.
• 22.
• MRI devices are used in medicine by sending short bursts of radio waves into the body
• A magnetic field helps the radio waves energize atoms and make them line up
• When the radio pulses are turned off they help create images of the body tissues
• 23.
• LANDSAT is a Canadian satellite that records how different parts of the light from the Sun reflect back to the satellite.
• It's most important use is for agriculture , monitoring crops for damage by disease, pests and drought.
• 24.
• RADARSAT is a Canadian telecommunications satellite, which, sweeps the ground below it with radio waves, penetrating fog, haze, clouds and rain.
• The reflection back to the satellite gives scientists information they can use in their studies of the Earth.
• E.g. Monitoring ice floes , search for minerals, oil and natural gas , monitoring a flood .
• 25.
• Microwaves have the shortest wavelength and the highest frequency of the all the radio waves .
• Microwaves have three characteristics that allow them to be used in cooking :
• they are reflected by metal ;
• they pass through glass, paper, plastic, and similar materials ;
• they are absorbed by foods .
• 26.
• Microwaves are used to detect speeding cars , to send telephone, satellite and television communications, and to treat muscle soreness .
• Industries use microwaves to dry and cure plywood , to cure rubber and resins , to raise bread and doughnuts , and to cook potato chips .
• The most common consumer use of microwave energy is in microwave ovens .
• Microwave ovens have been regulated since 1971 .
• 27.
• Just beyond the violet part of the visible spectrum are wavelengths of about 200 nm ., known as ultraviolet (UV) radiation.
• This radiation is very energetic . It causes tanning, but it can also do irreparable damage to us. UV rays can damage the cornea of the eye.
• More UV radiation is reaching us because the ozone layer in the atmosphere (which protects us from the damaging radiation by absorbing the UV rays) is being thinned .
• This thinning of the ozone layer is speeded-up by the use of aerosol sprays and Freon gas , which break up the ozone particles .
• 28.
• 29.
• 30.
• Red light has a wavelength of about 700 nm . It could be stretched out to 100 nm and it would become heat (infrared) radiation. It would become invisible to the eyes, but you could sense it with your skin.
• Anything that is warmer than its surroundings emit infrared rays .
• Practical Applications include:
• motion sensors
• burglar alarms
• heat lamps
• 31.
• 32.
• Even shorter wavelengths with higher frequencies are the X-rays.
• These waves pass through tissue (skin and muscle) and are absorbed by the bones .
• This radiation always stays in the bone and builds up over time.
• People who work as technicians taking the x-rays must protect themselves, by leaving the room where the x-ray is taken and also protect the patient's other areas of the body with lead vests to prevent over-exposure.
• 33.
• 34.
• Gamma rays have the shortest wavelength and the highest frequency of all the waves in the electromagnetic spectrum.
• Gamma rays result from nuclear reactions and can kill cells .
• This can be useful if the cells being destroyed are harmful - like cancerous cells .
• The cancerous growth of cells and tissue can be radiated and is known as radiation therapy .
• 35.
• 36.
• ... describe some of the technological applications of electromagnetic spectrum radiation?
• ... recognize the dangers associated with certain forms of radiation?
• 37.
• #3. Why is it a good idea to wear a hat and sun block creams when spending time in the sun?
• ________________________________________________________________________________________________________
• #4. Explain how radio waves can be used to determine the position of icebergs at sea?
• ________________________________________________________________________________________________________
• #5. EMR can be used to treat cancer. What type of radiation would you use if you were an oncologist (cancer specialist)? Explain.
• ________________________________________________________________________________________________________