Magnets

Question 1

What are the two poles of a magnet called?

Answer 1

The north pole and the south pole.

Question 2

Where is the magnetic force strongest?

Answer 2

Near the poles.

Question 3

Which poles of a magnet attract each other?

Answer 3

Two unlike poles (1 north and 1 south pole)

Question 4

What happens between like poles (N–N or S–S)?

Answer 4

They repel each other.

Question 5

What kind of force is magnetism?

Answer 5

A non-contact force

Question 6

What is the difference between a permanent and induced magnet?

Answer 6

Permanent magnets produce their own magnetic field and cannot be turned on and off.
Induced magnets only become a magnet when placed in a magnetic field. They lose most or all of their magnetism when they are removed from the magnetic field.

Question 7

Name 4 magnetic materials (materials that can be attracted by a magnet)

Answer 7

Iron, steel, nickel and cobalt are magnetic materials.

Question 8

Draw the magnetic field lines around a bar magnet.

Answer 8

Question 9

What is wrong with the magnetic field lines in this diagram?
A direction of magnetic field is wrong
B magnetic field lines are crossing each other
C magnetic field lines are not parallel
D there are only 3 magnetic field lines near the poles.​

Answer 9

B. Field lines should never overlap.

Question 10

What feature of field lines shows the strength of the magnetic field?

Answer 10

The closer the lines, the stronger the magnetic field (so the magnetic field from a bar magnet is strongest closest to the poles)

Question 11

The direction of the magnetic field at any point is given by the direction of the force that would act on another _____ pole placed at that point.

Answer 11

North pole. Field lines should always point from north to south

Question 12

What simple piece of equipment allows you to detect a magnetic field line? How would you use this to draw the field lines for a bar magnet?

Answer 12

Place the plotting compass near the magnet on a piece of paper. Mark the direction the compass needle points. Move the plotting compass to many different positions in the magnetic field, marking the needle direction each time. Join the points to show the field lines.

Question 13

Explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.

Answer 13

• Magnets always point to the earth’s north pole.
• This tells us that the earth must have a magnetic field.
• It is predicted that this is produced by magnetic iron in the earths core

Question 14

What type of force does induced magnetism always cause?

Answer 14

An attractive force

Question 15

Answer 15

i) Both pointing towards the S pole
ii) Permanent Magnet

Question 16

Answer 16

This shows the magnetic field getting weaker as distance increases

Question 17

What is a solenoid?

Answer 17

A wire coiled up into a spiral shape. When a current passes through it it creates a magnetic field similar to a bar magnet.

Question 18

How would you describe the field inside this solenoid?

Answer 18

It is uniform (show by the lines that are parallel and evenly spaced)

Question 19

A solenoid with an iron core is called an electromagnet. What effect does the iron core have on the solenoid’s magnetic field strength.

Answer 19

It increases it.

Question 20

Name 2 other things other than an iron core that could increase the strength of an electromagnet.

Answer 20

1. Adding more turns to the solenoid.
2. Increasing the current through the solenoid.

Question 21

What is an advantage of an electromagnet over a permanent magnet?

Answer 21

They can be turned on and off
and
The strength of the magnetic field can be varied

Question 22

Explain how the electromagnet and conveyor belt are used to separate the steel cans from the aluminium cans.

Answer 22

Steel cans are attracted to the electromagnet and are transferred to the container (by the conveyor belt). Aluminium cans are not attracted to the electromagnet and are left behind on the table

Question 23

Answer 23

Mark where the compass points on the paper Move the compass to the marked point
Repeat until you get back to the magnet
Join up the points
Add an arrow pointing from the north pole to the south pole.

Question 24

Magnetic materials include:

a) Steel, plastic and wood

b) Iron, nickel and cobalt

c) Iron, aluminium and cobalt

Answer 24

B is correct

Question 25

Answer 25

B as all domains are aligned

Question 26

Order the statements to explain
how a circuit breaker works

A. The circuit is broken and current stops flowing.

B. An electrical fault occurs.

C. The force is large enough so the soft iron bolt moves out of its slot.

D. The force from the electromagnet attracting the iron bolt increases.

E. This causes a current larger than the overload current to flow through the electromagnet.

F. The spring loaded switch can move to the open position.

Answer 26

B, E , D, C , F , A