Answer:
Amplitude modulation is used in AM radio.
Step-by-step explanation:
Information signals must be transported between a transmitter and a receiver on some form of transmission medium. However, information signals rarely find a suitable way to transmit. Therefore, modulation is defined as the process of transforming information from its original form to a form more suitable for transmission, and is performed on the transmitter in a circuit called a modulator.
AM means modulated amplitude or amplitude modulation; it consists in varying the amplitude of a carrier wave of relatively high frequency according to the amplitude of the modulating signal (information). Frequencies that are high enough to radiate efficiently through an antenna and propagate through free space are commonly called radio frequencies.
AM was the first technique that was used to make radio.
Then amplitude modulation is used in AM radio.