Sound Into Electricity

Microphones perform the same broad transformation: sound waves (pressure changes in air) become electrical signals. They do not all use the same mechanism. Dynamic microphones use a moving coil and magnet; condenser and MEMS microphones detect changes in capacitance.

In a dynamic microphone, the coil vibrates inside a magnetic field, and Faraday's law kicks in: a moving conductor in a magnetic field generates electric current. The frequency of the sound wave becomes the frequency of the electrical signal, reproducing the original waveform closely rather than perfectly.