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Unformatted text preview: Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Two radio antennas are 120 m apart on a north south line. The two antennas radiate in phase at a frequency of 3.4 MHz. All radio measurements are made far from the antennas. The smallest angle, reckoned east of north from the antennas, at which constructive interference of two radio waves occurs, is closest to: A) 47 B) 34 C) 38 D) 30 E) 43 1) 2) Two radio antennas are 100 m apart on a north south line. The two antennas radiate in phase at a frequency of 4.9 MHz. All radio measurements are made far from the antennas. The smallest angle, reckoned north of east from the antennas, at which destructive interference of the two radio waves occurs, is closest to: A) 22 B) 13 C) 27 D) 8.9 E) 18 2) 3) Two radio antennas are 130 m apart on a north south line. The two antennas radiate in phase at a frequency of 4.7 MHz. All radio measurements are made far from the antennas. Point A is due east of the antennas and point B is 30 north of east from the antennas. Both points A and B are at the same large distance from the antennas. The ratio of the intensity of the radio signal at B to that at A is closest to: A) 1.0 B) 1.5 C) 3.0 D) 0.50 E) 2.0 3) 4) Two radio antennas are 10 km apart on a north south axis on a seacoast. The antennas broadcast identical AM radio signals, in phase, at a frequency of 8.20 MHz. A steamship, 200 km offshore, travels due north at a speed of 15 km/hr and passes east of the antennas. A radio on board the ship is tuned to the broadcast frequency. The reception of the radio signal on the ship is a maximum at a given instant. The time interval until the next occurrence of maximum reception is closest to: A) 5.1 min B) 2.2 min C) 3.7 min D) 4.4 min E) 2.9 min 4) 5) Two radio antennas are 10 km apart on a north south axis on a seacoast. The antennas broadcast identical AM radio signals, in phase, at a frequency of 6.80 MHz. A steamship, 200 km offshore, travels due north at a speed of 15 km/hr and passes east of the antennas. A radio on board the ship is tuned to the broadcast frequency. Four minutes after a radio signal of maximum intensity is received, the ratio of the intensity of the signal received to the maximum intensity is closest to: A) 0.25 B) 0.50 C) 0.83 D) 0.93 E) 0.88 5) 1 Figure 35.1a 6) An FM radio transmitter, operating at a frequency of 120 MHz, is atop a 100 m tower. An airplane is in ight over the ocean at an altitude of 2000 m. Radio waves reach the airplane directly from the transmitter and by reection from the surface of the ocean. When the airplane is 86 km from the tower, the pilot observes that radio reception has faded due to destructive interference of the waves in the two paths. Assume the wave reected from the ocean surface has undergone a half wave phase shift. In Fig. 35.1a, the waves of the reected path arrive at the airplane...
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This note was uploaded on 12/13/2011 for the course PHYS 2C PHYS 2C taught by Professor Groisman during the Spring '11 term at UCSD.
 Spring '11
 groisman

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