Loudspeakers and Microphones

Question 1

How are loudspeakers and microphones similar?

Answer 1

They both convert between sound waves and electrical signals

Question 2

How do loudspeaker convert electrical signals into sound waves?

Answer 2

Using the motor effect

Question 3

How do microphones convert sounds waves into electrical signals?

Answer 3

Using the generator effect

Question 4

What type of current is involved with microphones and loudspeakers?

Answer 4

Alternating current

Question 5

How does the inside of a loudspeaker look and how does it work?

Answer 5

A loudspeaker consists of a coil of wire which is wrapped around one pole of a permanent magnet and connected to a cone.

1. An alternating current flows through the wire and
   creates a magnetic field in the coil
2. This magnetic field interacts with the other magnetic field of the iron core and will exert a force on the coil (motor effect)
3. As the current is alternating, it will cause the coil of wire to rapidly move back and forth, which will make the cone vibrate
4. These vibrations cause sound waves

Question 6

How does the inside of a microphone look and how does it work?

Answer 6

There is a coil wrapped around a pole of a magnet. This coil is attached to a diaphragm.

1. Sound waves hit the diaphragm
2. This causes diaphragm, and therefore coil of wire to move
3. Coil of wire moving in the magnetic field of the magnet induces a current in the wire (Electromagnetic Induction)
4. The frequency and amplitude of the sound waves will determine on how much the diaphragm vibrates