1. THE ELECTROMAGNETIC SPECTRUM
WAVES
THE ELECTROMAGNETIC SPECTRUM
Essential Question: What are the wave variables and how do they relate to each other?

2. Electromagnetic Spectrum
R O Y G B I V
Wavelength (λ) in meters
Visible light
10-14
10-12
10-10
10-8
10-6
10-4
10-2
100
102
104
Gamma rays
Ultraviolet
Infrared
Radio
Microwave
X rays
TV, FM AM
1022
1020
1018
1016
1014
1012
1010
108
106
104
Frequency (f) in Hertz
High Energy
Low Energy

3. Waves are the result of a vibration
traveling from one location to another.
Waves are a method that enrgy uses to travel from one location to another
velocity
Wave
Energy input
(vibration)

4. Types of Waves
Longitudinal or compression – vibrate parallel to velocity. ex. Sound
Transverse – vibrations perpendicular to velocity. ex. Light and water waves

5. Crest Amplitude .r λ f Wavelength (λ) in meters 1 Hertz Trough 2 Hertz
Frequency (f) in Hertz
(Waves per Second)
Crest
Amplitude
Vertical displacement
1 Hertz .r
1 second
Trough λ
2 Hertz f
3 Hertz

6. Period and Frequency of Vibrations
period – time (seconds) it takes for 1 vibration (wave) to occur.
frequency – number of vibrations (waves) in a second
f = 1/p AND p = 1/f
10Hz has a period of 1/10th of a second
Unit: s
Unit: Hz or s-1

7. 1 second
Period = 1/10 or 0.1
.1s
.2s
.3s
.4s
.5s
.6s
.7s
.8s
.9s 1s
f =
10 Hz

8. Electromagnetic Spectrum

9. Wave Uses

10. Relative Wavelength

11. What type of wave is it? Use EM spectrum λ = 2.90 x 10-8 m
f = 6.35 x 10 Hz
λ = 7.01 x 10-6 m
λ = 9.40 x m
f = 1.52 x 1022 Hz
f = 3.99 x 108 Hz
λ = 8.34 x m
f = 2.76 x 1010 Hz

12. Calculating frequency, wavelength, period and velocity
Symbol
Unit
Equation
Wavelength λ
(Lambda)
Meters (m)
λ = v/f
Frequency f
Hertz (Hz, s-1)
f = v/λ
f = 1/p
Period p s
1/f
velocity of light v*
Meters per second (m/s)
v = f λ
v = velocity
*Speed of light
(3.00 x10 8) c
c = f λ

13. Draw continuous Y axis 4 sq from left side all the way down
Calculate amplitude sq Count down from the top this many squares and draw your x axis all the way across
Dots represent wavelength, dashes represent half a wavelength: calculate # of sq. for wavelength and make your dots (number of dots is determined by # of vibrations)
In between each dot along your x axis make your dashes
Calculate # of sq. for amplitude. Make a dot in between dashes and dots up the correct number of dots. Alternate this for crest and trough
Connect the dots to form your wave.

14. In any other medium you have to calculate velocity
Speed of Light
Speed of light (c) in a vacuum =
3.00 x108 meters per second (m/s)
In any other medium you have to calculate velocity
v=fλ
Vacuum
Water

15. Going around the world 7.5 times a second
How fast is the speed of light?
Going around the world 7.5 times a second

16. What is the wavelength. What is the frequency
What is the wavelength? What is the frequency? What is the speed of the wave?
The wavelength of an x-ray is 4.32 x m. What is its frequency?
Ultraviolet radiation from the sun has a frequency of 2.49 x 1016 Hz. What is its wavelength?
An infrared ray has a frequency of 1.01E10 Hz and a wavelength of x 10-2 m. What is the speed of the wave?
3.00x108 m/s
4.32x10-11 m f =
c/λ
6.94 x1018 Hz = =
3.00x108 m/s
2.49x1016 s-1 λ =
c/f
1.20x10-8 m = =
2.98x108 m/s
1.01x1010 Hz x 2.95x10-2 m =

17. Radio Stations Radio stations transmit their signal in megahertz (MHz)
1 megahertz = ? Hertz
106
98.5 MHz
106 Hz
9.85x 107 Hz x = 1 1
MHz

18. Radio Station’s Wavelength
What is the wavelength of these radio stations?
97.9 MHz (you have to convert to Hz first)
104.5 MHz
105.3 MHz
9.79 x 107 Hz
λ = c/f
3.06 m
λ = c/f
1.045 x108 Hz
2.87 m
λ = c/f
1.053 x108 Hz
2.85 m

19. Interference
Interference occurs when 2 waves occupy the same space at the same time.
It can be “destructive” or “constructive”, depending if the waves are “in phase” or “out of phase”.

20. Interference
Destructive
Constructive + = + =

21. v=fλ In a vacuum v = (c) speed of light
In any other medium you have to calculate velocity
Faster =  f or ↓ λ
Slower = ↓f or  λ

22. Color Wavelengths λ (m) R O Y G B I V Color 7.00E-7 6.50E-7 6.00E-7

23. Baaaaaaa!
Lambda!

24. A B C D
2 Hertz λ f
3 Hertz

25. 1 sec

26. 1 sec

27. 1 sec

28. 1 sec

29. Title
Period (time 1 swing)
Mass 1
Mass 2
Mass 3
Mass 4

30. Title 3 Period (time 1 swing) s No breaks! 0.25 m 0.50 m 0.75 m 1.00 m
0.25 m
0.50 m
0.75 m
1.00 m
1.00 m
String length (m)