Chapter 35, Problem 35.53P

DATA Short-wave radio antennas A and B are connected to the same transmitter and emit coherent waves in phase and with the same frequency f. You must determine the value of f and the placement of the antennas that produce a maximum intensity through constructive interference at a receiving antenna that is located at point P, which is at the corner of your garage. First you place antenna A at a point 240.0 m due east of P. Next you place antenna B on the line that connects A and P, a distance x due east of P, where x < 240.0 m. Then you measure that a maximum in the total intensity from the two antennas occurs when x = 210.0 m, 216.0 m, and 222.0 m. You don’t investigate smaller or larger values of x. (Treat the antennas as point sources.) (a) What is the frequency f of the waves that are emitted by the antennas? (b) What is the greatest value of x, with x < 240.0 m, for which the interference at P is destructive?