Answer Happy

QP 35 Two dipole antennas are located on opposite ends of a lake and emit electromagnetic radia- tion with wavelength A. A boat moves along the line connecting the two emitter antennas. The boat carries a receiver antenna that picks up the emitted radiation. Figure ?? sketches the situation emitter receiver emitter ))) Groen Top view emitter bont emitter FIG. 1: (a) Suppose for now that the two emitters radiate electromagnetic waves with the same amplitude. As the boat sails towards the left emitter antenna, the receiver picks up an oscillatory signal due to interference from the two incoming waves. When the boat is midway between the antennas, the detected signal is found to be maximal ("bright' fringe). The signal's amplitude first drops down to zero ("dark' fringe) after the boat traverses a distance d leftward. What is d in terms of the wavelength X? (You can assume that the emitters and receiver all lie along a straight line.) (b) Suppose next that the amplitude of the ac drive applied to the left antenna is increased, so that the two emitters radiate electromagnetic waves with different amplitudes (but still a common wavelength ). Does the fringe spacing detected by the boat's receiver change relative to the case where the amplitudes are equal? Why or why not? (c) Let the ratio of amplitudes for the electromagnetic waves emitted by the left and right antennas be 2:1. What is the ratio of the intensity of bright and dark' fringes picked up the boat's receiver antenna?