Microphones (GCSE Physics)

Microphones

Using the Generator Effect

In microphones we see the opposite to what happens in a loudspeaker, where we used variations in current to generate pressure variations in sound waves.

Here, we are generating variations in the current using the variations in the pressure of sound waves.

Moving Coils in Microphones

1. Moving coils are used in devices. In previous tutorials we have seen that lots of devices use moving coils inside them to generate a current. Here, we are going to look at how they work in microphones.
2. A cone vibrates. A cone in the microphone vibrates. This cone is in contact with a coil of wire. The coil will move and start to rotate.
3. The coil generates a current. When the coil rotates in the magnetic field, it will generate a current.
4. The current can be controlled. We can control the size of the current by changing the variations in the sound waves. If the sound is loud, then the cone will vibrate more, meaning that a larger current is generated. The current can go on to be used in an electric circuit.