1. 17.3 Behaviors of Waves Reflection Refraction Diffraction
Constructive Interference
Destructive Interference
Standing Waves

2. Reflection
When a wave bounces off a surface that it cannot pass through
Ex. – ball can’t pass through a wall, so it bounces off
Reflection does not change the speed or frequency of a wave, but the wave can be flipped upside down
Fixed boundary  reflected wave upside down

3. Refraction The bending of a wave as it enters a new medium at an angle
Occurs when a wave enters a medium at an angle
One side of the wave moves more slowly than the other side
Refraction applet
In this case, v = different refractive value for a different medium

4. Diffraction

5. Diffraction PhET diffraction applet
The bending of a wave as it moves around an obstacle or passes through a narrow opening
A wave diffracts more if its wavelength is large compared to the size of an opening or obstacle
If wavelength < opening/obstacle, then very little bending
If wavelength > opening/obstacle, then larger bending

6. Interference When 2 or more waves overlap and combine together
2 types of interference
Constructive (leads to increased amplitude)
Destructive (leads to decreased amplitude)

7. Constructive interference
When 2 or more waves combine to produce a wave with a larger displacement (amplitude)

8. Destructive Interference
When 2 or more waves combine to produce a wave with a smaller displacement (amplitude)

9. Standing Waves
A wave that appears to stay in one place – it does not seem to move through the medium
Examples – plucked guitar string or elastic cord
Node = a stationary point on a standing wave
Complete destructive interference between incoming and reflected waves
Antinode = a point where a crest or trough occurs midway between nodes
Forms only if a wavelength or a multiple of half a wavelength fits exactly into the length of a vibrating cord.

10. Standing Waves Links to Standing Waves Applets
Standing wave created by reflecting off of 1 barrier
Standing wave created by reflecting off 2 barriers