Chapter 34 293 Q34.16 The voltage induced in the loop antenna is proportional to the rate of change of the magnetic field in the wave. A wave of higher frequency induces a larger emf in direct proportion. The instantaneous voltage between the ends of a dipole antenna is the distance between the ends multiplied by the electric field of the wave. It does not depend on the frequency of the wave. Q34.17 The radiation resistance of a broadcast antenna is the equivalent resistance that would take the same power that the antenna radiates, and convert it into internal energy. Q34.18 Consider a typical metal rod antenna for a car radio. The rod detects the electric field portion of the carrier wave. Variations in the amplitude of the incoming radio wave cause the electrons in the rod to vibrate with amplitudes emulating those of the carrier wave. Likewise, for frequency modulation, the variations of the frequency of the carrier wave cause constant-amplitude vibrations of the electrons in the rod but at frequencies that imitate those of the carrier. Q34.19
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