Electromagnetism

Question 1

Magnetic field lines always point from

Answer 1

north to south.

Question 2

The arrow on a magnetic field line shows

Answer 2

the direction the north pole of a compass would point if you placed it there.

Question 3

A magnet placed near unmagnetised iron will

Answer 3

attract it, since iron is a magnetic material.

Question 4

A magnet placed near unmagnetised steel will

Answer 4

attract it, since steel is a magnetic material.

Question 5

A magnet placed near copper will

Answer 5

not attract or repel the copper. Copper is not a magnetic material.

Question 6

Two north poles placed close together will

Answer 6

repel.

Question 7

Two south poles placed close together will

Answer 7

repel.

Question 8

A north pole and a south pole placed close together will

Answer 8

attract.

Question 9

The ‘motor effect,’ describes how a wire feels a force if it is in a magnetic field and

Answer 9

it is carrying a current.

Question 10

The ‘motor effect,’ describes how a wire feels a force if carries a current and

Answer 10

it is in a magnetic field.

Question 11

Fleming’s left hand rule can be used to solve problems involving the ‘motor effect.’ What does the thumb represent?

Answer 11

Motion; in other words, the direction of the force on the wire.

Question 12

Fleming’s left hand rule can be used to solve problems involving the ‘motor effect.’ What does the first finger represent?

Answer 12

The direction of the magnetic field, pointing from north to south.

Question 13

Fleming’s left hand rule can be used to solve problems involving the ‘motor effect.’ What does the second finger represent?

Answer 13

The direction of the electric current, pointing from positive to negative.

Question 14

What rule can be used to solve problems involving the motor effect?

Answer 14

Fleming’s left hand rule.

Question 15

A current carrying coil of wire in a magnetic field experiences a force. (The ‘motor effect’) How could this force be increased? (4 ways)

Answer 15

Increase the current in the coil.
Add more turns to the coil.
Make each turn of the coil bigger.
Increase the magnetic field strength.

Question 18

When a wire cuts through magnetic field lines a current is induced in it. How can the induced current be increased? (2 ways)

Answer 18

Move the wire faster.

Use a stronger magnetic field.

Question 19

What rule can be used to work out the direction of magnetic field lines around a straight current-carrying wire?

Answer 19

The right hand grip rule.

Question 20

The ‘generator effect’ describes how a current is induced when

Answer 20

a conductor cuts through magnetic field lines.

Question 21

How can the magnetic field around a current carrying solenoid be increased? (4 ways)

Answer 21

Increase the current in the solenoid.
Add more turns to the solenoid.
Increase the area of each turn on the solenoid.
Add a soft iron core, turning the solenoid into an electromagnet.

Question 22

How can the magnetic field around a current carrying electromagnet be increased? (3 ways)

Answer 22

Increase the current in the electromagnet.
Add more turns to the electromagnet.
Increase the area of each turn on the electromagnet.

Question 23

What is a uniform magnetic field?

Answer 23

When the magnetic field lines are straight, parallel and equally spaced.

Question 24

How can a uniform magnetic field be produced?

Answer 24

By bringing the north and south poles of two bar magnets close together. There will be a uniform magnetic field in the gap between them.

Question 27

What is an example of a ‘hard’ magnetic material?

Answer 27

Steel.

Question 31

What is a magnetic material?

Answer 31

A material that can be magnetised, i.e. turned into a magnet.

Question 32

What does it mean if a magnetic material is described as ‘soft’?

Answer 32

The material is easily magnetised and demagnetised.

Question 33

What is an example of a ‘soft’ magnetic material?

Answer 33

Iron.

Question 34

What does it mean if a magnetic material is described as ‘hard’?

Answer 34

The material cannot be easily magnetised. Once magnetised, it is difficult to demagnetise.

Question 35

How could the magnetic field between two magnets be strengthened?

Answer 35

Move them closer together.