Electromagnets + The Motor Effect

Question 0

Which material, iron or steel is used as the core of an electromagnet?

Answer 0

Iron

Question 1

Which material, iron or steel is used to make a permanent magnet?

Answer 1

Steel

Question 2

State whether there is a force of attraction or repulsion when:

1: A magnet is held near a unmagnetised iron bar
2: The north pole of a bar magnet is placed near the north pole of a second bar magnet
3: The north pole of a bar magnet is placed near the south pole of a second bar magnet

Answer 2

1: No forces
2: Repulsion
3: Attraction

Question 3

Do opposite poles attract or repel?

Answer 3

Opposite poles attract, like poles repel

Question 4

What is a magnetic field?

Answer 4

The line along which a plotting compass points

Question 5

What does an electromagnet consist of?

Answer 5

A coil of insulated wire wrapped round a iron core.

Question 6

What are electromagnets used for?

Answer 6

Scrapyard cranes, circuit breakers, electric bells and relays.

Question 7

Complete the statements with these words:
Coil, current, force, magnet

1: When a ________ passes through the ________ of an electric motor, a ________ acts on each side of the ________.
2: The ________ along each side is in opposite directions so the ________ is in opposite directions and the ________ turns.

Answer 7

1: When a current passes through the coil of an electric motor, a force acts on each side of the coil.
2: The magnet along each side is in opposite directions so the force is in opposite directions and the coil turns.

Question 8

Explain why a simple electric motor connected to a battery reverses if the battery connections are reversed

Answer 8

Because the force pushing the coil up or down on each side is reversed.

Question 9

A force is exerted on a straight wire when a current is passed through it and it is at right angles to the lines of a magnetic field. Describe how the force changes if the wire is turned through 90 degrees until it is parallel to the magnetic field.q

Answer 9

The force would decrease as it becomes less perpendicular to the magnetic field, stopping altogether as it becomes parallel to the magnetic field.

Question 10

Complete the statements with these words:
Magnetic field, conductor, current, potential difference

1: A ________ is induced in a ________ when it cuts across the ________ lines.
2: If a ________ connected to an ammeter moves parallel to the lines of a magnetic ________ no ________ passes through the ammeter.

Answer 10

1: A potential difference is induced in a conductor when it cuts across the magnetic field lines.
2: If a conductor connected to an ammeter moves parallel to the lines of a magnetic field no current passes through the ammeter.

Question 11

What is electromagnetic induction?

Answer 11

Electromagnetic induction is the process of creating a potential difference using a magnetic fields.