1. Wave Interactions

2. Reflection
The interaction of a wave with a surface it cannot pass through.
Causes the wave to bounce back.
Ex: Looking in a mirror – light
Ex: Echo – sound
Law of reflection – The angle the wave comes in at (incidence) = the angle the wave will be reflected at.

3. - Interactions of Waves
Refraction

4. Refraction Occurs when: AND The bending of waves.
Due to a change in speed.
Occurs when:
Enters a new medium
Enters it at an angle
AND
One side of the wave enters first and changes speed first, causing the wave to bend.

5. Diffraction When a wave moves around a barrier
When a wave moves through a hole or opening in a barrier. OR

6. - Interactions of Waves
Diffraction

7. Interference Interaction between waves that meet (run into each other)
2 types
Constructive (build up)
Destructive (tear down)

8. Constructive Interference
- Interactions of Waves
Constructive Interference
When waves combine to make a wave with a larger amplitude.
When crest meets crest or trough meets trough.
Add their energies

9. Destructive Interference
The interference that occurs when waves combine to make a wave with a smaller amplitude.
Subtract their energies

10. Standing Waves A wave that appears to stand still in one place.
Actually 2 waves interfering as they pass through each other.
When an incoming wave meets a reflected wave at just the right frequency.

11. Standing waves cont. Node: Point of zero amplitude on a standing wave.
Min. energy
Antinode: Point of maximum amplitude on a standing wave.
Max. energy

12. Resonance When external vibrations match an objects natural frequency
Increases the amplitude of the vibration