Magnetism

Question 1

What is a magnetic field line?

Answer 1

A graphical representation of the direction and magnitude of a magnetic field

Question 2

How would you use two permanent magnets to produce a uniform field pattern?

Answer 2

Place them next to each other horizontally with two opposing poles faving each other

Question 3

What happens when an electrical current is passed through a conductor?

Answer 3

A magnetic field is produced

Question 4

How do you find the direction of the magnetic field around a wire?

Answer 4

The right-hand rule

Question 5

What happens when a current is passed through a wire then placed in a magnetic field?

Answer 5

A force is produced which acts on the wire

Question 6

How does a loudspeaker work?

Answer 6

1. An alternating current is passed through a coil in a magnetic field
2. Results in alternating forces in the coil.
3. The coil is attached to a coil that transfers the vibrations to the air

Question 7

How does an electric motor work?

Answer 7

1. A current flows through the coil
2. The current in the wire creates a magnetic field
3. The two fields interact
4. This exerts a force on either side of the coil
5. The commutator reverses the current every half turn, reversing the forces which keeps the coil spinning.

Question 8

What happens when a conductor is moved through a magnetic field?

Answer 8

A voltage is induced in the wire

Question 9

How do you increase the voltage induced in a wire?

Answer 9

1. Cut the field faster

2. Use stronger magnets

Question 10

How do you speed a motor?

Answer 10

1. More current
2. More turns on the coil
3. Stronger magnets
4. Soft iron core in the middle

Question 11

What do transformers change?

Answer 11

ALTERNATING voltages

Question 12

What is the name of a transformer that increases voltages?

Answer 12

A step-up transformer