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Class
Interactions of Waves
Inquiry Warm-Up, How Does a Ball Bounce?
In the Inquiry Warm-Up, you investigated angles of reflection by observing how a ball
bounces. Using what you learned from that activity, answer the questions below.
1. EXPLAIN How does a ball bouncing show one of the ways that waves
can change direction?
2. DESCRIBE How would you describe the reflection of a wave?
3. APPLY CONCEPTS If a ball is rolled and hits a wall at an angle of 35°,
would it then continue rolling along the wall? Explain why or
why not?
4. APPLY CONCEPTS What angle of reflection would occur if a wave hits a
surface at an angle of 45°?
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Class
Interactions of Waves
What Changes the Direction of a Wave?
1a.
DEFINE What is diffraction?
b. CLASSIFY A wave bends after entering a new medium. What type of
interaction is this? ________________________________________________________________
I get it! Now I know that a wave’s direction can be changed by ______________________________
I need extra help with _____________________________________________________________
What Are the Two Types of Wave Interference?
I get it! Now I know that the two types of wave interference are _____________________________
I need extra help with _____________________________________________________________
Name
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Class
Interactions of Waves
How Do Standing Waves Form?
2a.
b.
DESCRIBE What causes resonance to occur?
RELATE CAUSE AND EFFECT What causes nodes to form in a
standing wave?
I get it! Now I know that standing waves form when ______________________________________
I need extra help with _____________________________________________________________
Name
Date
Interactions of Waves
On a separate sheet of paper, explain how standing waves form.
Class
Name
Date
Class
Interactions of Waves
Understanding Main Ideas
If the statement is true, write true. If the statement is false, change the underlined word
or words to make the statement true.
1. __________________ Waves change direction by diffraction, reflection,
and deflection.
2. __________________ Constructive interference is used in
some headphones to block out distracting noises in a listener’s
surroundings.
3. __________________ If an incoming wave and reflected wave have
a high-pitched frequency, they combine to form a standing wave.
Building Vocabulary
Match each term with its definition by writing the letter of the correct definition in the
right column on the line beside the term in the left column.
4. ___ diffraction
a. interaction of two waves that results in a wave with a
larger amplitude
5. ___ interference
b. a wave that appears to stay in one place
6. ___ constructive interference
c. increase in amplitude that occurs when external
vibrations match an object’s own natural frequency
7. ___ destructive interference
d. interaction of two waves that results in a wave with a
smaller amplitude
8. ___ standing wave
e. the bending and spreading out of waves around the
edge of a barrier
9. ___ resonance
f.
interaction between two waves that meet
Name
Date
Class
Interactions of Waves
Read the passage and study the diagrams. Then use a separate sheet of paper to answer
the questions that follow.
Interference of Pulses
If you and a friend hold a rope between you and one of you flicks the rope, the wave that travels along
the rope is called a pulse. If you and your friend each give an upward flick to the rope at the same time,
two pulses will travel down the rope in opposite directions. Figure 1 shows what happens as the pulses
travel through each other.
Figure 2 shows what would happen if you gave an upward flick to the rope at the same time as your
friend gave a downward flick to the rope. When these two pulses travel through each other, their
amplitudes also “combine.” but in this case, the amplitude of the downward pulse is “subtracted” from
the amplitude of the upward pulse.
1. Does Figure 1 show constructive or destructive interference?
Figure 2? Explain.
2. The pulse traveling toward the left in Figure 1A has an amplitude of
2 cm. The pulse traveling toward the right has an amplitude of 4 cm.
What is the amplitude of the pulse in Figure 1C?
3. Refer to question 2. What are the amplitudes of the pulses in
Figure 1E?
4. The pulse traveling toward the left in Figure 2A has an amplitude of
3 cm. The pulse traveling toward the right has an amplitude of 5 cm.
What is the amplitude of the pulse in Figure 2C?
Name
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Class
Interactions of Waves
Write the letter of the correct answer on the line at the left.
1. ___ Reflection occurs when a wave
2. ___ Refraction occurs when a wave
A bends due to a change in speed
A bends due to a change in speed
B hits a surface and bounces back
B hits a surface and bounces back
C passes through an opening
C passes through an opening
D bends around a barrier
D bends around a barrier
3. ___ Interference in which waves combine
to form a wave with a larger amplitude
than either wave originally had is called
A destructive interference
B amplitude enhancement
C constructive interference
4. ___ Points of maximum amplitude on a
standing wave are called
A crests
B incidence
C apexes
D antinodes
D resonance
Fill in the blank to complete each statement.
5. Destructive interference in a standing wave produces points with zero amplitude
called _________________.
6. Waves do not bend when entering a new medium at a(n) _________________
angle.
7. A wave refracts because one side of the wave changes _________________before
the other side.
8. A wave _________________ and spreads out in diffraction.
9. When the crest of one wave overlaps the trough of another wave,
___________________________________ can occur.
10. A standing wave is actually two waves _________________ as they pass through
each other.
Interactions of Waves
Answer Key
1. Answers will vary. Sample: A ball bounces
back from a wall at the same angle it hits the
wall. Waves change direction like a ball, which
bounces off a surface at the same angle it hits
the surface.
2. Answers will vary. Sample: When a wave hits
a surface, it bounces back at the same angle
at which it hits a surface.
3. Answers will vary. Sample: No, the ball would
not roll along the wall because the angle of
reflection would not be the same as the angle
the ball hit the wall. A ball would bounce from
the wall at an angle of 35°.
1. Figure 1 shows constructive interference. When
the two pulses pass through each other, they
combine to make a pulse with larger amplitude.
Figure 2 shows destructive interference. When
the two pulses pass through each other,
they combine to make a pulse with a smaller
amplitude.
2. 6 cm
3. The amplitude of the pulse traveling to the
right is 4 cm, and the amplitude of the pulse
traveling to the left is 2 cm.
4. 2 cm
4. The wave would reflect at an angle of 45º.
Answers will vary. Sample: In a standing wave,
destructive interference produces points with zero
amplitude, called nodes. The nodes are always
evenly spaced along the wave. At points in the
standing wave where constructive interference
occurs, the amplitude is greater than zero. Points
of maximum amplitude on a standing wave are
called antinodes.
1. refraction
2. Destructive
3. just the right
4. e
5. f
6. a
7. d
8. b
9. c
1. B
2. A
3. C
4. D
5. nodes
6. right
7. speed
8. bends
9. destructive
interference
10. interfering