SECTION 3 Wave Behavior
In your textbook, read about wave behavior.
For each statement below, write true or rewrite the italicized part to make the statement true.
1. __________________________
When a wave encounters a boundary, the wave that strikes the
boundary is called the incident wave.
2. __________________________
When a wave encounters a boundary, the wave that returns to the
original medium is called the refracted wave.
3. __________________________
When a wave from a light, flexible spring passes into a heavier,
stiffer spring, almost all of the wave’s energy is reflected back to
the light spring.
4. __________________________
When a wave is sent down a spring connected to a wall, none of
the energy in the wave is reflected back.
5. __________________________
When interference produces standing waves in a rope, the rope
appears to be standing still.
Answer the following questions. Use complete sentences.
6. What happens when a wave moves across a boundary from one medium to another? Consider
two springs, one large and one small, joined end-to-end. Describe the wave pulse moving from a
large spring into a smaller one. Explain what happens to the energy in the incident wave.
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7. What is the principle of superposition?
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8. Draw a diagram of wave fronts and rays that represents refraction. Label the boundary. Use
arrows to show the change in direction.
In your textbook, read about waves in two dimensions.
Answer the following questions. Use complete sentences.
9. What is a wave front?
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10. When is a wave refracted?
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11. A ray diagram shows the direction of wave motion. What is the normal? What does it show?
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12. What is the angle of incidence? What is the angle of reflection?
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13. What is the law of reflection?
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14. What causes an echo?
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15. What happens when a wave moves from deep to shallow water? How does the frequency
change?
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Answers
SECTION 3 Wave Behavior
1. true
2. reflected wave
3. some
4. most
5. true
6. The incident wave strikes the boundary, then one pulse from the larger spring continues in the
smaller spring, but at the specific speed of waves traveling through the smaller spring; some of
the energy of the incident wave’s pulse is reflected back into the larger spring.
7. The principle of superposition states that when two waves are superposed, the displacement of
the medium at the site of superposition is the algebraic sum of the displacements caused by the
individual waves.
8.
9. A wave front is a line that represents the crest of a wave in two dimensions.
10. A wave is refracted when a wave crosses a boundary and changes direction.
11. The normal is the line drawn perpendicular to the barrier in a ray diagram; it shows the direction
of the barrier.
12. The angle of incidence is the angle between the normal and the incident
ray; the angle of reflection is the angle between the normal and the reflected ray.
13. The angle of incidence is equal to the angle of reflection.
14. The reflection of sound off a hard surface causes an echo.
15. The wave’s speed decreases and the wave’s direction changes. The wave’s frequency does not
change.