What component is most commonly used as an audio detector in an AM radio?

In an AM radio, the most commonly used component for audio detection is the diode. The diode's main function in this context is to demodulate the amplitude-modulated signal by detecting the variations in amplitude that carry the audio information. When an AM signal is applied to the diode, it allows current to flow only in one direction, effectively extracting the audio signal from the modulated carrier wave. This process is known as envelope detection, which converts the varying amplitude of the AM signal back into the original audio waveform.

Other components, such as transistors, capacitors, and inductors, play important roles in various parts of an AM radio circuit, but they do not primarily function as audio detectors. Transistors, for instance, can be used for amplification but are not specific to the detection process. Capacitors and inductors are often involved in tuning and filtering but do not perform the actual demodulation of the AM signal. Therefore, the diode stands out as the key component for audio detection in AM radios.