A microphone is a transducer that converts a mechanical (acoustic) wave to an electrical signal. From this point of view,  it is the symmetrical oppposite of  a loudspeaker. There are different types of microphones. In each case, we find something vibrating under the influence of a sound wave and the use of a physical law to convert this mechanical vibration to an electric signal.

Pedagogical overview of the symmetry between electricity and magnetism and the corresponding laws.

The electromagnetic spectrum. Note the relationship between frequency and wavelength.

The dynamo uses electromagnetic induction to convert mechanical circular motion into an alternating electric voltage. Such induction can only occur if the magnet and the coil are in relative motion.

The generator is based on Faraday's law of induction. It transforms mechanical energy into electrical energy as in a  power plant.

Induction occurs when the flux of B through a closed loop varies. The intensity of B according to the loop surface varies.

Induction occurs when the flux of B through a closed loop varies. The orientation of B relative to the loop surface varies.

Keep in mind that this experiment is the basis for the principles underlying many power plants.

An alternator converts mechanical energy (from rotation) into electrical energy via electromagnetic induction. This is the core of most of our electrical power plants, and is how all electricity is generated except in electrochemical systems (batteries, photovoltaic cells…).

The process can be monophasic (as with a single dynamo) or triphasic (as in power plants).