Moving-Coil Microphones

What effect is used in a moving-coil microphone?

The generator effect.

What is the purpose of a microphone?

To convert sound waves into variations in an electrical signal.

What are the main components of a moving-coil microphone?

A diaphragm, coil of wire and permanent magnet.

What happens when sound waves reach the microphone diaphragm?

The changing air pressure causes the diaphragm to vibrate.

What happens to the coil when the diaphragm vibrates?

The coil moves backwards and forwards in the magnetic field.

Why does movement of the coil produce a potential difference?

The coil moves relative to the magnetic field, producing an induced potential difference.

Why does the induced potential difference vary?

The coil's speed and direction of movement change as it vibrates.

How does a microphone produce an alternating electrical signal?

The vibrating coil moves in opposite directions, reversing the induced potential difference.

How does the frequency of the electrical signal relate to the sound?

It follows the frequency of the sound vibrations.

How does louder sound generally affect the electrical signal?

It produces larger diaphragm vibrations and usually a greater signal amplitude.

Why is a permanent magnet needed in a moving-coil microphone?

It provides the magnetic field needed for induction.

What is the main energy transfer in a microphone?

Energy from sound waves is transferred into an electrical signal.

What is the difference between a moving-coil microphone and a loudspeaker?

A microphone uses the generator effect, whereas a loudspeaker uses the motor effect.

Why can a microphone detect changes in sound pressure?

The diaphragm responds to pressure variations in the sound wave.

What happens if the diaphragm does not vibrate?

There is no changing magnetic field through the coil, so no alternating signal is induced.