1. The Electromagnetic Spectrum
Wavelength/frequency/energy
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The Electromagnetic Spectrum

2. What is it?
The electromagnetic spectrum is the complete spectrum or continuum of light including radio waves, infrared, visible light, ultraviolet light, X- rays and gamma rays
An electromagnetic wave consists of electric and magnetic fields which vibrates thus making waves.
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The Electromagnetic Spectrum

3. Waves Properties of waves include speed, frequency and wavelength
Speed (s), frequency (f) and wavelength () are related in the formula  x f = s
All light travels at a speed of 3 s 108 m/s in a vacuum
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The Electromagnetic Spectrum

4. Wavelength, Frequency and Energy
Since all light travels at the same speed, wavelength and frequency have an indirect relationship.
Light with a short wavelength will have a high frequency and light with a long wavelength will have a low frequency.
Light with short wavelengths has high energy and long wavelength has low energy
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The Electromagnetic Spectrum

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The Electromagnetic Spectrum

6. Radio waves Low energy waves with long wavelengths
Includes FM, AM, radar and TV waves
Wavelengths of 10-1m and longer
Low frequency
Used in many devices such as remote control items, cell phones, wireless devices, etc.
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The Electromagnetic Spectrum

7. Microwaves Longer than radio, shorter than light and infrared
Wavelength 1 x m to 1 x m
First used in radar, now used in communication, medicine and consumer use (microwave ovens)
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The Electromagnetic Spectrum

8. Infrared waves
Invisible electromagnetic waves that are detected as heat
Can be detected with special devices such as night goggles
Used in heat lamps
Higher energy than microwaves but lower than visible light
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The Electromagnetic Spectrum

9. Visible Light
The portion of the electromagnetic spectrum that human eyes can detect
ROY G BIV (red, orange, yellow, green, blue, indigo, violet)
Red is the lowest frequency and violet is the highest frequency
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The Electromagnetic Spectrum

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The Electromagnetic Spectrum

11. Ultraviolet waves Higher energy than light waves
Can cause skin cancer and blindness in humans
Used in tanning beds and sterilizing equipment
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The Electromagnetic Spectrum

12. X-Rays High energy waves First discovered by Roentgen
Used in medicine, industry and astronomy
Can cause cancer
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The Electromagnetic Spectrum

13. Gamma rays Highest energy Blocked from Earth’s surface by atmosphere
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The Electromagnetic Spectrum

14. Time to think…..
1. What is the relationship between frequency and wavelength?
2. What is meant by ‘spectrum’?
3. What does ROY G BIV mean?
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The Electromagnetic Spectrum

15. Now, let’s really think 4. Can you actually see x-rays?
Support your answer.
5. Which color is more energetic, red or yellow?
6. Which type of wave travels faster, gamma or radio?
7. Why are microwaves more dangerous than radio waves?
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The Electromagnetic Spectrum

16. Think about it….
You have just been involved in a traffic incident that leaves you stranded on the side of the road. Which part of the electromagnetic spectrum would be of the most use to you and why?
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The Electromagnetic Spectrum

17. Answers
1. Frequency and wavelength are properties of waves and since speed is constant for em waves, as frequency increases, wavelength decreases.
2. Spectrum is a continuum of all electromagnetic waves
3, ROY G BIV is the difference colors of the visible light in order of longest wavelength to shortest wavelength.
4. X-rays can not be seen, only the waves in the visible light portion are visible.
5. Yellow is higher energy than red because it has a shorter wavelength and higher frequency.
6. Both travel at the same speed, 300,000 km/s (all em waves travel at the same speed)
7. Microwaves have a higher frequency than radio and carry more energy.
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The Electromagnetic Spectrum