F.5 physics (wave)

2010-12-28 2:12 am

1. Describe how to produce continuous straight water waves in a ripple tank.2. With reference to the figure, explain briefly how the TV signals at the house are affected by the airplane.

圖片參考：http://imgcld.yimg.com/8/n/HA00005851/o/701012270100113873432170.jpg

回答 (1)

天同

2010-12-28 3:54 am

✔ 最佳答案

1. Use a straight edge vibrator.

2. There are two waves reaching the receiving antenna, one is directly from the transmitter and the other one is reflected by the aeroplane. Since there is a path difference between the two waves at the receiving antenna and which leads to a phase difference, interference occurs. If the path difference is a multiple of the wavelength of the TV signals, constructive interference occurs and a strong signal is received by the antenna. On the other hand, if the the path difference is half a wavelength, destructive interference occurs and a weak signal is received.

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