College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 86

Radio waves from a star, of wavelength 250 m, reach a radio telescope by two separate paths, as shown in Figure P24.13. One is a direct path to the receiver, which is situated on the edge of a cliffby the ocean. The second is by reflection offthe water. The first minimum of destructive interference occurs when the star is = 25.0° above the horizon. Find the height of the cliff. (Assume no phase change on reflection.)