1. Electromagnetic Waves
Students will be able to
Describe polarity
Reproduce the entire spectrum
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2. Where?
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3. What is an Electromagnetic Wave
Wave that transfers energy without a medium
Vibration of electric and magnetic fields that
move through space at the speed of light
Created by moving an electric charge
Called electromagnetic radiation
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4. Speed
Speed in a vacuum 300,000 kilometers per second
From sun to Earth?
8 minutes
Light slows down when it enters a medium
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5. Models
Wave Model
Light travels in many directions at once
Polarizing filters block all but light in one direction
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6. Models
Particle Model
Light is a tiny particle moving through space
Called photon
Light bump up electrons in atoms
Called photoelectric effect
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7. Electromagnetic Spectrum
All electromagnetic waves travel at same speed
Vary only in wavelengths and frequencies
Waves you can see are called visible light
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8. Radio Waves
Long wavelength
Low frequency
Purpose
Broadcast Waves for TV and Radio
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9. Microwaves
Shortest radio waves
Cell phones
Radar (Radio Detection And Ranging)
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11. Infrared Rays
Heat waves that you feel but can not see
Heat Lamps
Infrared Cameras
Warmer objects give off more waves than cold
Satellites
Locate people
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12. Visible Light
Small part of electromagnetic spectrum
Longest waves = Red
Shortest waves = Violet
Visible light is a mixture of all wavelengths – White
When bending in a new medium red bends least
The color you see is what is reflected
(rest of light is absorbed)
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13. Ultraviolet Rays
Much shorter waves than visible light (more energy)
Very dangerous
Cause damage
Cancer cells
Eye damage
Kill bacteria (used in hospitals/labs)
Sunscreen and sunglasses used to black these rays
Ozone layer blocks many of these rays
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14. X-Rays
High energy
Penetrates most tissues
Blocked only by very dense structures
Bone / Lead
Used in medicine and structural analysis to look for
damage
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15. Gamma Rays
Extremely high energy
Used in medicine to kill cancer cells
Can not penetrate Earth atmosphere
Telescopes put into space to detect
Discovery of astronomical events
Stars, black holes, galaxies…
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16. Review
• Polarization
• Spectrum
– Radio Waves
– Microwaves
– Infrared
– Visible Light
– Ultraviolet
– X-Ray
– Gamma

17. Quiz

18. Homework
Draw and label the electromagnetic
spectrum. Describe one thing of
importance for each part of the spectrum.