1. Wave Basics Or, How to Destroy a Slinky Without Even Trying… D Taylor © 2008

2. 2 nd Semester Shtuff Topics left Waves & Sound (this week) Heat & Thermo (Throw Away Topic) Electricity (3 wks) Magnetism (0.1 wks) Electromagnetism (1 week) Optics (2 wks) Atomic/Nuclear Physics (2 wks) Lions & Tigers, & Bears! Oh, MY!

9. Basic Terminology Wavelength – DUH! Displacement of a sinusoidal periodic wave along the independent coordinate. i.e. The length of the wave. ‘ ’.

11. Tesladownunder Diversion

23. Basic Terminology Pulse Single disturbance ½ Pulse

25. Can you say, “Idiot”?

26. Basic Terminology Period Time required for one complete wavelength. ‘T’ Unit - Seconds

27. Basic Terminology Frequency # wavelengths per second f = 1/T Unit – 1/sec, sec -1, Hz (Hertz)

31. Tech-TV Blunder!

32. Basic Terminology Amplitude Disturbance along the vertical. Height of wave as measured from x-axis A

33. Basic Terminology Velocity of waves?

34. Wave Motion gifs Ext LINK Wave Combo Examples LAB 25 stuff Weird Wave World Doppler & Co.

37. Waves -Advanced Stuff Tighten your seatbelt… It’s getting’ bumpy!

40. Video of Invisibility Cloak

41. Advanced Wave Stuff Sound Intensity Logarithmic Function (HUH?)  =10 log I/I o I o = 1 x 10 -12 W/m 2 Chart pg 475

46. Intensity I (W/m 2) Intensity  (dB) Threshold of human hearing 1 x 10 -12 0 Leaves rustling1 x 10 -11 10 Whisper1 x 10 -10 20 Normal Conversation @ 1 m 3 x 10 -16 65 Inside car1 x 10 -4 80 Car w/o muffler1 x 10 -2 100 Live rock concert 1120 Pain10130 Taylor Mad1 x 10 488 5000

56. A log excursion…

58. LAB 25 LAB 25 Ext Link

62. Advanced Wave Stuff Sound Intensity Problems? One sound produces a  1 = 90dB and another is  2 = 93dB. What is the ratio I 2 /I 1 ?

71. Advanced Wave Stuff Doppler Effect? Occurs when a sound or an observer moves in the direction of the sound! (Say WHAT?) Sirens, Moving cars, Planes… Resonance tube Demo Tuning Fork Demo

74. Ugly Doppler Math

75. = Apparent Frequency = Actual Frequency = Object’s Velocity = Source Velocity = Sound Velocity TOP Sign = TOWARD

77. Apps & Probs A little pot-bellied kid is standing in the waves unattended. He notices 10 waves crash against his little chubby legs in 2 minutes. What is the frequency of these ocean waves?

80. Apps & Probs Two boats are hanging out 10 meters from each other. As the waves go by, one boat is at max up while the other is max down and no crests are between them. What’s the wavelength of the water waves?

83. Apps & Probs A boat is anchored. Over the side is a rope ladder with rungs one foot apart and there’s 8 of them visible above the waterline. The tide comes in and rises at a rate of ½ foot per hour. After 5 hours, how much of the rope ladder is still visible above the waterline?

84. DUH!

86. Apps & Probs The wavelength of a sound in air is 2.74m @ 20 o C. What is its wavelength if it enters fresh water at 20 o C?

89. Wave Motion & Interference Reflection Refraction Diffraction Resonance

90. Wave Motion & Interference Reflection i=r (duh…)

91. Wave Motion & Interference Refraction Bending of a wave entering or exiting media. (mediums?)

92. EM Spectrum

93. Less Basic Wave Stuff i r Why?

94. Wave Fronts: “crests” Direction of wave travel

95. What happens to ? What happens to f? What happens to v?

96. Wave Motion & Interference Diffraction Bending of a wave around an obstacle OR thru an opening