1. The Electromagnetic Spectrum

2. What is the Electromagnetic Spectrum?
The electromagnetic spectrum is the complete spectrum (or continuum) of all forms of “light”
An electromagnetic wave consists of electric and magnetic fields which vibrate - thus making waves.
Vibrations

3. What is the Electromagnetic Spectrum?
The electromagnetic spectrum consists of:
radio waves
cell phone waves
microwaves
radar waves
infrared waves
visible light waves
ultraviolet waves
x-ray waves
gamma waves
The Electromagnetic Spectrum

4. The Electromagnetic Spectrum

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

6. Relationship Between Wavelength & Frequency
All parts of the electromagnetic spectrum travel at the same speed
Therefore, wavelength and frequency have an indirect relationship.
This means that as one characteristic increases, the other decreases
In other words, as wavelength increases, frequency decreases
The Electromagnetic Spectrum

7. Relationship Between Wavelength & Frequency
As wavelength decreases, frequency will?
increase
See the relationship
The Electromagnetic Spectrum

8. Wavelength, Frequency, Energy
Electromagnetic wave characteristics:
short wavelengths have a high frequency
long wavelengths have a low frequency
Electromagnetic waves & Energy:
high frequency waves have high energy
low frequency waves have low energy
The Electromagnetic Spectrum

9. Wavelength, Frequency, Energy
Fill in the table below:
wavelength
frequency
energy
long
high
The Electromagnetic Spectrum

10. Wavelength & Energy
smaller wavelengths
increasing frequency
increasing energy
If you haven’t already, sketch this drawing into your notes. Don’t worry so much about the actual wavelengths, just get the general shape and where the various forms of light (radio, infrared, x-ray, etc) exist.
The Electromagnetic Spectrum

11. The Electromagnetic Spectrum

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

13. Microwaves Only radio waves are longer
Wavelength 1 x m to 1 x m (1 m to m)
used for communication, medicine and consumer use (microwave ovens)
The Electromagnetic Spectrum

14. 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
The Electromagnetic Spectrum

15. red has the lowest frequency – violet the highest
Visible Light
The portion of the electromagnetic spectrum that human eyes can detect
ROY G BIV (red, orange, yellow, green, blue, indigo, violet)
Which color has the lowest frequency?
red has the lowest frequency – violet the highest
The Electromagnetic Spectrum

16. The Electromagnetic Spectrum

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

18. X-Rays High energy waves Used in medicine, industry and astronomy
Can cause cancer
The Electromagnetic Spectrum

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

20. The Electromagnetic Spectrum

21. Time to remember...
What is the relationship between frequency and wavelength?
What characteristic of gamma waves gives them their high energy?
What does ROY G BIV mean? What part of the electromagnetic spectrum does it refer to?
The Electromagnetic Spectrum

22. Time to Think Which color is more energetic, red or yellow?
Which type of wave travels faster, gamma or radio?
Why are microwaves more dangerous than radio waves?
The Electromagnetic Spectrum

23. Apply What You Know
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?
The Electromagnetic Spectrum

24. Answers
Frequency and wavelength are properties of waves and since speed is constant for em waves, as frequency increases, wavelength decreases. In other words, they have an indirect relationship.
Gamma waves get their high energy from their extremely short wavelengths (or extremely fast frequency)
ROY G BIV stands for “red, orange, yellow, green, blue, indigo, and violet. They are the colors of the visible light in order of longest wavelength to shortest wavelength.
Yellow is more energetic than red because it has a shorter wavelength (or larger frequency)
Gamma waves and radio waves travel at the same speed
Microwaves are more dangerous than radio waves because they have a higher frequency and carry more energy.
The Electromagnetic Spectrum

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The Electromagnetic Spectrum