Question

In an amplitude modulated wave for audio-frequency of 500 cycle/second, appropriate carrier frequency will be:
(A) 50 cycle/sec
(B) 100 cycle/sec
(C) 500 cycle/sec
(D) 50,000 cycle/sec

Answer 1

Hint: As we know the amplitude modulation is a modulation technique where the amplitude of the carrier wave is varied in proportion to the message signal so as to make the wave modulated. Also in amplitude modulation the frequency of the carrier wave is always greater than that of the modulated wave.

Complete Answer:
We know that modulation is the process of varying the properties of a wave using another wave called the carrier wave, which might contain the message/data/information signal that needs to be sent across a channel without any loss. In the practical world a device called modulator is used for wave modulation while a device called demodulator is used for the demodulation of the device.
Some of the widely known and used modulation techniques are:
-Amplitude modulation
-Frequency modulation
-Phase modulation
The amplitude modulation of a wave is nothing but modulating the data wave using a carrier wave, where only the amplitude of the carrier signal is varied in accordance with the amplitude of the modulating signal. Now it is clear that only the amplitude would vary on the carrier signal during amplitude modulation.
Thus we know that in an amplitude modulated wave the frequency of the carrier waves are going to be more than that of the audio signal. Thus if the frequency of the audio wave is 500 cycles per second then the carrier wave frequency that is more than that of the audio wave frequency is 50,000 cycles per second.
So the correct answer will be option D.

Note:
Just as in amplitude modulated waves, in the frequency modulated wave, the frequency of carrier signal is varied in accordance with the amplitude of the modulating wave. And in the phase modulated wave, the phase shift of the carrier signal is varied in accordance with the amplitude of the modulating signal.