Microphones
The microphone is a device that converts sound waves into electrical signals. Microphones use the When motion between a conductor and a magnetic field creates electricity, ie a magnet is moved into a coil of wire. to induce a changing current from the pressure variations of sound waves.
Moving-coil microphones
The diagram shows a A microphone in which electrical signals are produced when the pressure variations in sound waves vibrate a coil of wire within a magnetic field..
A moving-coil microphone
In a moving-coil microphone:
- pressure variations in sound waves cause the flexible diaphragm to vibrate
- the vibrations of the diaphragm cause vibrations in the coil
- the coil moves relative to a permanent magnet, so a The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them. is induced in the coil
- the coil is part of a complete circuit, so the induced potential difference causes a current to flow around the circuit
- the changing size and direction of the induced current matches the vibrations of the coil
- the electrical signals generated match the pressure variations in the sound waves