1. CHARACTERISTICS OF WAVES
Chapter 15, Section 2, pp

2. A. __________ AMPLITUDE REST CREST TROUGH ENERGY Earth Harp
The maximum movement of a wave from ________.
REST
CREST
Measured from rest to ________ (top of the wave) or rest to __________ (bottom).
TROUGH
ENERGY
Represents the amount of __________ carried by the wave
Ex: A sound wave with more energy and greater amplitude is __________
LOUDER!

3. AMPLITUDE

4. The intensity of an earthquake is determined by the _____________ of the original disturbance and waves.
AMPLITUDE
Earthquake energy measured by a
_________________.
SEISMOMETER

6. WAVELENGTH B. ______________ 
The distance between two equivalent parts of a wave.
Ex: from ________ to ________
CREST
CREST 
Symbol = ___
(Greek letter _______)
Lambda
unit = ______
meter

7. shorter wavelengths carry _______ energy than longer wavelengths.
MORE

9. C. _______
PERIOD
the time (seconds) required for one full _____________ of a wave to pass a certain point.
WAVELENGTH
Ex: Time between crests in a wave pool

11. FREQUENCY D. ________________
The number of complete waves per unit of time (waves/second)
Unit = _________.
Hertz (Hz)
1 Hz = 1 vibration / sec
Distinguishes one color of ______ from another, or whether or not a _______ is audible.
LIGHT
SOUND
Frequency = 1
T (period)

12. Frequency vs. Period Frequency Period How often something happens
Time it takes something to happen (start to finish)
Rate quantity
Time quantity
Cycles/second
Seconds/cycle
Example: If the woodpecker drums upon a tree 2 times in one second, then the frequency is 2 Hz. Each drum must endure for one-half a second, so the period is 0.5 s.

13. Floating along………
Suppose you are floating on an inner tube in the ocean. A wave crest passes the inner tube every 2 seconds.
Period: 2s (total time for one complete
wave/oscillation to occur)
Frequency: f = _1_ f = 1 T
f = 0.5 Hz

14. Different colors…
In the same medium, light travels at the _____ speed (300,000,000 m/s or 186,000 mph). What makes the colors different? ___________
SAME
frequencies…

15. Different sounds…
In the same medium, sound travels at the ______ speed. What makes differently pitched (high/low) sounds? _______________
SAME
the frequencies…
Ex: Humans hear from 20-20,000 Hz
Mosquito ring
tones

16. For two waves moving at the SAME speed, as  INCREASES, frequency ____________
DECREASES
In addition, as the period of a wave decreases, the frequency _____________ (INVERSE relationship)
INCREASES

17. Wave Speed
The speed of a wave depends on the ________.
MEDIUM
In a given medium, the speed of a wave is ____________.
CONSTANT
3,800 m/s
1500 m/s
340 m/s
WHY DOES SPEED DIFFER?

18. The speed of a wave is equal to wavelength divided by period, or to frequency multiplied by wavelength.
Remember… the speed of a moving object is found by dividing the ________ the object travels by the ____ it takes the object to travel that distance or… speed = distance / time (v = d / t)
distance
time

19. So… wave speed = wavelength ÷ periodλ V T
Because wave speed is the inverse of frequency, dividing by the period is equivalent to multiplying by the frequency.
Therefore the speed of a wave can also be calculated:
wave speed = frequency × wavelength
v = f x λ V f λ

20. Practice Problem
The string of a piano that produces the note middle C vibrates with a frequency of ____ Hz. If the sound waves produced by this string have a wavelength in air of ____ m, what is the speed of the sound waves?
Given: Unknown:
frequency, f = 262 Hz wave speed, v = ? m/s
wavelength, λ = 1.30 m
262
1.30

21. v = f x λ Variables: v= ? f= 262 Hz λ= 1.30m Equation =
Solution: v = 262 Hz x 1.30 m v = 341 m/s

22. The Doppler Effect
An observed change in the ____________ of a wave when the source of the wave or the observer is _________
FREQUENCY
MOVING

24. Fire Engine Siren Doppler
Train Horn Doppler
Fire Engine Siren Doppler

25. REDSHIFT
BLUESHIFT

26. Doppler Big Bang

28. More wave speed practice problems
1. The average wavelength in a series of ocean waves is _____ m. A wave crest arrives at the shore on average every ____ s, so the frequency is ______ Hz. What is the average speed of the wave?
15.0
10.0
0.100

29. 2. Green light has a wavelength of __________ m
2. Green light has a wavelength of __________ m. The speed of light is _________ m/s. Calculate the frequency of green light waves with this wavelength.
0.52
3,000

30. 3. The speed of sound in air is about _____ m/s
3. The speed of sound in air is about _____ m/s. What is the wavelength of a sound wave with a frequency of _____ Hz (on a piano, the A below middle C)?
340
220

31. 4. Calculate the frequency of microwaves that have a wavelength of _______ m and a speed of _________ m/s.
0.0085
3,000