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Unformatted text preview: Solutions Chapter 38 Due November 18 2004 Q38.2 The wavelength of light is extremely small in comparison to the dimensions of your hand, so the diffraction of light around an obstacle the size of your hand is totally negligible. However, sound waves have wavelengths that are comparable to the dimensions of the hand or even larger. Therefore, significant diffraction of sound waves occurs around hand-sized obstacles. Q38.4 An AM radio wave has wavelength on the order of 8 6 1 3 10 m s ~ 300 m 1 10 s- × × . This is large compared to the width of the mouth of a tunnel, so the AM radio waves can reflect from the surrounding ground as if the hole were not there. (In the same way, a metal screen forming the dish of a radio telescope can reflect radio waves as if it were solid, and a hole- riddled screen in the door of a microwave oven keeps the microwaves inside.) The wave does not “see” the hole. Very little of the radio wave energy enters the tunnel, and the AM radio signal fades. An FM radio waveenergy enters the tunnel, and the AM radio signal fades....
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