2. Ch 11 - Vocabulary  wave,  medium,  transverse wave,  longitudinal wave,  Standing wave  crest,  trough,  Rest position  Equilibrium position  Amplitude  wavelength,  frequency,  Period  vibration,  hertz,  velocity,  interference,  constructive interference,  destructive interference  Doppler Effect  Resonance  Reflection  refraction

3. Interactions of Waves Section 11-2 Two-Column Notes

4. 5 Types of Wave Interaction   Reflection   Refraction   Diffraction   Resonance   Interference

5. Slide 1  Reflection  When a wave hits a surface through which it cannot pass and bounces back  Angle of incidence equals angle of reflection  Angle of incidence is angle between incoming wave and perpendicular line MAIN IDEADETAILS

7. Reflection Angle of Incidence Angle of Reflection Barrier

8. Slide 2  What is Refraction  When a wave moves from one medium to another medium at an angle, it changes speed, causing it to bend MAIN IDEADETAILS

10. Refraction Angle of Incidence Angle of Reflection

11. Slide 3  What is Diffraction?  When a wave passes a barrier or moves through a hole in a barrier, it bends and spreads out. MAIN IDEADETAILS

12. Diffraction

13. Diffraction Animations

15. Slide 7  What is Resonance?  All objects have a ‘natural’ frequency.  Resonance occurs when vibrations traveling through an object match its ‘natural frequency’.  The object starts to vibrate at its ‘natural frequency’. MAIN IDEADETAILS

16. Resonance An object causes a nearby object to vibrate at its natural frequency, results in sound being amplified

17. Example When you pluck a guitar string and it vibrates at its natural frequency, the sound is louder

19. Slide 4  What is Interference?  What is Constructive Interference?  When 2 or more waves meet and have an effect on each other.  Occurs when two waves combine and ‘match up’ to create a bigger amplitude. MAIN IDEADETAILS

20. Constructive Interference Wave 1 Wave 2 Resulting Wave

21. Slide 5  What is Destructive Interference?  What is a Standing Wave?  When two waves combine on opposite trough/Crest and the waves cancel out.  When an incoming wave and reflected wave meet and the combined wave appears to be standing still. MAIN IDEADETAILS

22. Destructive Interference Wave 1 Wave 2 Resulting Wave

23. Standing Wave

24. Slide 6  What is a ‘Node’ and Antinode?  Node: Where ingoing and outgoing waves meet and destructive interference causes an amplitude of Zero.  AntiNode: where the crest and trough of the standing wave exist MAIN IDEADETAILS

25. Interference Animations

26. Constructive Interference

27. Destructive Interference

28. Effects of interference  Interference of light waves produces colors  Interference of sound waves produces beats

30. STANDING WAVES

32. A standing wave is a wave that is caused by interference and appears to not be moving. It has regions of no vibration and regions of maximum vibration.

33. Standing waves do not move through a medium, they cause the medium to vibrate in a loop or series of loops.

35. NODE - Area in wave of no vibration ANTINODE – Area in wave of maximum vibration (midway between nodes

37. Standing waves occur at frequencies that are multiples (harmonics) of the natural frequency of the string. The natural frequency is the frequency the object tends to vibrate at when disturbed.

39. Behavior of Waves- Doppler Effect The observed change in Frequency of a wave when the source or observer is moving

41. HOMEWORK PROJECT  DUE 4/13/09:  Design and construct a musical instrument that can play at least 3 different notes.  Be prepared to explain how your instrument creates sounds, and demonstrate to the class by playing your instrument and singing a song along with the demonstration.  You may have one (1) partner. If you make a wind instrument, one person has to play while the other sings or you have to get a friend to sing while you play.  REMEMBER: This is not music class, so you are not graded on the artistic value of your presentation, only that you did it. See attached grading handout.