1. WARM UP 11/5/15
In your IAN notebook, solve the following problem. Show ALL of your work including the formula you used and the units of the answer.
A tree 2736 ft. away from your position is struck by lightning. If you hear the thunder 2.5 seconds after the lightning hit, what is the speed of sound in this air?

2. Wave Interactions

3. 6 Wave Interactions
When a wave encounters a surface, 6 interactions can occur
Interference
Diffraction
Reflection
Absorption
Refraction
Polarization

4. Interference
Interference – when two or more waves meet in the same medium
Constructive Interference – when two waves add up to make a larger amplitude wave
Destructive Interference – when waves add up to make a smaller or zero amplitude wave (cancel each other out)

5. Constructive Interference

6. Constructive Interference
Crest to Crest Trough to Trough

7. Destructive Interference

8. Destructive Interference
Crest to Trough

10. Check for Understanding!1. 2.

11. Result of Interference
Resonance – occurs when vibrations travelling through an object match the object’s natural frequency
Also occurs when one object vibrates another object without touching it

12. Result of Resonance

13. Tacoma Narrows Bridge collapsing
Result of Resonance
Glass shattering
Tacoma Narrows Bridge collapsing
Chinook Helicopter

14. Reflection
Reflection – when a wave bounces off a material and goes in a new direction

15. Refraction
Refraction – when a wave passes through a different material and bends

16. Refraction

17. Diffraction
Diffraction – when a wave bends around corners

18. Absorption
Absorption – when a wave is absorbed by the material and may disappear

19. Polarization
Polarization – when EM waves move through a filter that blocks one direction of the wave.
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