How can solenoids be used to generate sound in speakers and microphones?

Question 1

What is a solenoid?

Answer 1

A solenoid is a long coil of wire.

Question 2

How can we increase the m.f. strength of a solenoid?

Answer 2

1. Increase current
2. Increase no. of turns
3. Add an iron core - the iron becomes an induced magnet.

Question 3

Describe the generator effect (electromagnetic induction).

Answer 3

When either a coil of wire moves in a m.f. or a magnet moves in a coil of wire and a p.d., and therefore a current, is induced.

Question 4

What is the direction of the induced current determined by?

Answer 4

The motion of the magnet.

Question 5

How can we increase the induced p.d?

Answer 5

1. Increase m.f strength
2. Increase no. of turns on the solenoid.
3. Increase speed of movement.

Question 6

How do microphones work? Give the 3 steps.

Answer 6

1. Sound waves make diaphragm vibrate, causes solenoid to vibrate around magnet.
2. induces a p.d and t.f an ac
3. electrical signals generated match frequency of sound waves.

Question 7

How do loudspeakers work? Give the 3 steps.

Answer 7

1. An a.c flows through the solenoid, creating a magnetic field, and moving the coil back and forth.
2. According to Flem. LHR, the interaction between the two m.f generates a force that pushes the cone outwards.
3. The cone moves b/c the coil moves, creating pressure variations in the air.