What waveform is used in amplitude modulation (AM)?

In amplitude modulation (AM), the unique characteristic is that the amplitude of a carrier wave is varied in accordance with the amplitude of the audio signal or information being transmitted. This means that the waveform used in AM is indeed a varying amplitude signal that directly represents the audio information. When the audio signal changes, the amplitude of the carrier wave is adjusted to match those changes, creating a modulated signal that contains the information to be transmitted.

This varying amplitude enables the receiving equipment to demodulate the signal and recover the original audio information. The carrier part of the waveform remains at a constant frequency, but its amplitude fluctuates based on the instantaneous values of the audio input, which is crucial for effective AM broadcasting.