17.3 Behavior of Waves
Reading Focus
Key Concepts
How does reflection change a wave?- What causes the refraction of a wave when it enters a new medium?
- What factors affect the amount of diffraction of a wave?
- What are two types of interference?
- What wavelengths will produce a standing wave?
Vocabulary
reflection
refraction
diffraction
interference
constructive interference
destructive interference
standing wave
node
antinode
Reading Strategy
Identifying Main Ideas Copy and expand the table below. As you read, write the main idea of each topic.
Topic |
Main Idea |
|---|---|
Reflection |
a. |
Refraction |
b. |
Diffraction |
c. |
Interference |
d. |
Standing waves |
e. |
Have you ever noticed bright lines like those shown in Figure 8 dancing on the bottom of a pool? These lines are produced when light shines through waves on the surface of the water. The lines don't seem to have a pattern because there are so many waves interacting. Imagine following just one of these waves. What will happen when it strikes the side of the pool? When it encounters another wave or an obstacle like a person? As the waves crisscross back and forth, many interactions can occur, including reflection, refraction, diffraction, and interference.
Reflection
The next time you are in a pool, try to observe ripples as they hit the side of the pool. Reflection occurs when a wave bounces off a surface that it cannot pass through. The reflection of a wave is like the reflection of a ball thrown at a wall. The ball cannot go through the wall, so it bounces back.
Figure 8 The ripples visible on the bottom of the pool are caused by light shining through surface waves.
If you send a transverse wave down a rope attached to a wall, the wave reflects when it hits the wall. Reflection does not change the speed or frequency of a wave, but the wave can be flipped upside down. If reflection occurs at a fixed boundary, then the reflected wave will be upside down compared to the original wave.
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