Question 189: EM waves

Question

In amplitude modulation,

Accepted Answer

Amplitude Modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In AM, the amplitude (the strength or intensity) of the carrier wave is varied in proportion to that of the message signal, such as an audio signal. This variation in amplitude represents the information or data that is being transmitted.
Given the options:
Option A suggests that only the frequency of the carrier wave changes according to the information signal, which is not true for amplitude modulation. In frequency modulation (FM), it is the frequency that changes according to the information signal, not the amplitude.
Option B correctly describes amplitude modulation. In AM, the amplitude of the carrier wave changes in accordance with the amplitude of the information signal, while the frequency of the carrier wave remains constant.
Option C suggests that both amplitude and frequency of the carrier wave change according to the information signal. This description does not fit AM but rather describes more complex modulation schemes where both amplitude and frequency can be varied, such as amplitude and frequency modulation techniques used together or other forms of digital modulation.
Option D suggests that in amplitude modulation, both the amplitude and frequency of the carrier wave do not change according to the information signal. This option is incorrect because, in AM, it is specifically the amplitude of the carrier wave that changes to encode information.
Therefore, the correct answer is:
Option B: amplitude of carrier wave changes according to information signal

Answer

amplitude remains constant but frequency . changes according to information signal

Answer

amplitude of carrier wave changes according to information signal

Answer

both amplitude and frequency changes according to information signal

Answer

both amplitude and frequency do not change according to information signal

EM waves

In amplitude modulation,

Choose the correct answer: