Wave Properties Study Guide
8th Grade PSI
Name ____________________________________
Directions: Define the following terms and/or concepts.
1. Wave
2. Equilibrium/Rest position
3. Transverse Wave
4. Crest
5. Trough
6. Amplitude
7. Wavelength
8. Frequency
9. The Wave equation (be familiar with all symbols in the equation)
10. Reflection
11. Refraction
12. Diffraction
13. Constructive Interference
14. Destructive Interference
15. Decibel
16. Longitudinal Wave
17. Compression
18. Rarefaction
19. Echolocation
20. The Doppler Effect
Directions: Select/State the answer that best completes the statement or answers
the question. Show work when appropriate.
1. If water is undisturbed and there is no wave observed, it can be said that the
water is in a (n)
a. undisturbed/rest position
b. Doppler effect
c. destructive interference
d. crest
2. When there is a disturbance in a medium and a wave is created, the particles in
that medium move away from their rest position. After this occurs, what do the
particles do?
a. They continue to move away and never return
b. They bounce back and return to their rest position
c. They stay frozen in space
d. They disappear
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8th Grade PSI
Wave Properties
3. How do a “pulse” and a “wave” compare?
4. A medium can be any
a. solid
b. liquid
c. gas
d. All of the above
5. The particles in a transverse wave vibrate at right angles to the direction of
energy movement.
a. True
b. False
For questions 6 and 7, use the following diagram.
A
B
6. Box A is pointing to a ________ on a wave.
a. crest
b. trough
7. Box B is pointing to a ________ on a wave.
a. crest
b. trough
8. ________ is the distance away from the rest position of a wave. Its symbol is y.
a. Frequency
b. Wavelength
c. Crest
d. Amplitude
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8th Grade PSI
Wave Properties
9. The symbol for wavelength is the Greek letter
a. Lambda (λ)
b. Beta (B)
c. Gamma
d. Phi
10. Period and frequency are inversely related to one another.
a. True
b. False
11. What is the velocity of a wave that has a wavelength of 10 cm and a frequency
of 2 Hz?
12. What is the velocity of a wave that has a wavelength of 5 m and a frequency of 5
Hz?
13. What is the frequency of a wave traveling at 200 m/s when it’s wavelength is 10
m?
14. What is the wavelength of a wave that is traveling at 63 m/s when it’s frequency
is 21 Hz?
15. When waves hit a boundary or an obstacle and are reflected, they
a. continue through the obstacle
b. disappear
c. bounce back
d. break apart
16. When refraction occurs, which changes, the wavelength or the frequency?
a. Wavelength
b. Frequency
17. When is diffraction most notable?
a. When the wavelength of the waves are much bigger in size than the
opening they are passing through
b. When the wavelength of the waves are much smaller in size than the
opening they are passing through
c. When the wavelength of the waves are similar in size to the opening they
are passing through
18. Diffraction is increased when waves pass through a large opening.
a. True
b. False
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8th Grade PSI
Wave Properties
19. When waves that are in phase (both vibrating in the same direction) with each
other add up in amplitude to reinforce each other and get bigger, _____ occurs.
a. Constructive Interference
b. Destructive Interference
20. When waves that are out of phase (both vibrating in the opposite direction) with
each other cancel out their amplitudes and get smaller, _______ occurs.
a. Constructive Interference
b. Destructive Interference
21. The smaller the vibrating object, the lower the frequency sound produced.
a. True
b. False
22. The SI unit for sound intensity is:
a. hertz
b. amplitude
c. frequency
d. decibel
23. As a vibrating object swings forward, it creates compression in the medium that
moves outward. This is an area of
a. high pressure
b. low pressure
24. When the vibrating object swings backward, it creates a rarefaction. This is an
area of
a. high pressure
b. low pressure
25. Choose the correct timeline of events which make up the “Path of Hearing”
I.
II.
III.
IV.
The waves vibrate bones (hammer, anvil, stirrup)
The cochlea changes vibrations into electrical impulses
Sound waves strike the eardrum
The signal is sent through the auditory nerve to the brain
a.
b.
c.
d.
IV, III, I, II
III, I, II, IV
III, I, IV, II
I, III, IV, II
26. The ear
a. is part of the auditory system
b. aids in balance and body position
c. is an organ that detects sound
d. All of the above
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Wave Properties
27. The “reflection of sound” is known as a(n) ________.
a. decibel
b. cochlea
c. echo
d. hertz
28. SONAR uses the reflection of sound waves to map the sea floor of our oceans.
a. True
b. False
29. Bats can use echolocation, which uses ___________ sound waves, to “see” how
far away food is.
a. refracted
b. diffracted
c. reflected
30. What is the speed of sound in air if a sound wave travels 3,000 meters in 10
seconds?
31. What is the speed of sound in air if a sound wave travels 2,424 meters in 3
seconds?
32. How far away from a wall are we if a sound returns in 5 seconds (NOTE: speed
of sound is 343 m/s)?
33. Describe, in terms of wavelength and frequency, what an observer may hear
from a moving sound source as the source approaches the observer, and then
moves away from the observer.
34. An observer moves toward a stationary alarm from a car going off. The moving
observer hears
a. A lower pitched sound
b. A higher pitched sound
c. The same pitch that is produced
35. The same observer turns around and begins to walk away from the blaring car
alarm. The moving observer hears
a. A lower pitched sound
b. A higher pitched sound
c. The same pitch that is produced
36. When is a sonic boom produced?
37. Traveling faster than the speed of sound is called “supersonic”.
a. True
b. False
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8th Grade PSI
Wave Properties
Answer Key
16. wave that vibrates the medium
parallel (in the same plane) to the
direction of wave motion
17. region of high pressure in a
longitudinal sound wave that
corresponds to a crest of a wave
18. region of low pressure in a
longitudinal sound wave that
corresponds to a trough of a
wave
19. determining the distance/location
of an object (food) by using
reflected sound waves
20. change in frequency of a wave
due to relative motion between
an observer and the wave source
Definitions
1. a disturbance that travels through
space or matter
2. the position of a particle in a
medium when it is undisturbed
3. a wave where the particles in the
medium vibrate perpendicular to
the wave energy propagation
4. point of maximum displacement
above equilibrium
5. point of maximum displacement
below equilibrium
6. maximum distance away from
rest position (above or below
equilibrium)
7. distance a wave travels before its
cycle repeats, measured crest to
crest/trough to trough
8. number of vibrations a wave
makes per second, measured in
Hz
9. v = λf (v= wave speed, lambda=
wavelength, f=frequency)
10. when a wave strikes a boundary
or an obstacle and bounces back
towards the source
11. change in direction of a wave due
to a change in its speed as it
goes through a different medium
12. bending of waves around small
objects and the spreading out of
waves past small openings
13. waves that are in phase (both
vibrating in the same direction)
with each other add up in
amplitude to reinforce each other
and get bigger
14. waves that are out of phase (both
vibrating in the opposite direction)
with each other cancel out their
amplitudes and get smaller
15. SI unit for sound intensity,
measures loudness
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Multiple Choice/Short Answer/TrueFalse
8th Grade PSI
1. A
2. B
3. A pulse is a single disturbance
that moves outward. A wave is a
series of pulses that produces
repeating and periodic
disturbances in the medium.
4. D
5. A- True
6. A
7. B
8. D
9. A
10. A-True
11. 20 cm/s
12. 25 m/s
13. 20 Hz
14. 3 m
15. C
16. A
17. C
18. B-False
19. A
20. B
21. B-False
Wave Properties
22. D
23. A
24. B
25. B
26. D
27. C
28. A-True
29. C
30. 300 m/s
31. 808 m/s
32. 857.5 m
33. As the sound source approaches,
the observer will hear a higher
pitched sound. This is due to a
higher frequency and a lower
wavelength of the sound waves.
When the source moves away
from the observer, the pitch will
sound lower. The sound waves at
this moment are of lower
frequency and higher
wavelength.
34. B
35. A
36. A sonic boom is produced when
a sound source is moving faster
than the speed of sound.
Constructive interference occurs
when the sound source “catches”
up with the sound waves it
produces. This creates a wave
with an increased amplitude or a
“sonic boom”.
37. A
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8th Grade PSI
Wave Properties