Ch1_part1_EPO460

Which material shows strong attraction to magnetic fields and retains its properties after the external field is removed?

• Diamagnetic

• Paramagnetic

• Ferromagnetic

• Non-magnetic

Magnets always have:

• One pole only

• Two poles

• Four poles

• No poles

Which of the following is a permanent magnet?

• Transformer core

• Fridge door magnet

• Paper clip

• Electromagnet in a motor

What happens to a temporary magnet (e.g. a nail near a magnet) once the external magnet is removed?

• It stays magnetised forever

• It loses magnetism after a short time

• It turns into a permanent magnet

• It becomes diamagnetic

An electromagnet becomes stronger when:

• Current is reduced

• Coil is replaced with a straight wire

• Core is ferromagnetic

• Air is used as core

The symbol for magnetic flux is:

• H

• B

• Φ

• M

The unit of magnetic flux density (B) is:

• Weber (Wb)

• Tesla (T)

• Ampere-turn (At)

• Henry (H)

Which rule is used to find the direction of magnetic field around a current-carrying conductor?

• Fleming’s left hand rule

• Fleming’s right hand rule

• Right-hand grip rule

• Lenz’s law

Faraday’s first law states:

• A coil stores energy in magnetic field

• A conductor cutting magnetic flux induces EMF

• Current flows in a closed loop only

• Flux density is proportional to magnetising force

Does the fringing effect increase if the air gap length increases?

• True

• False