Magnetism

Question 1

What is meant by the ‘poles’ of a magnet?

Answer 1

The poles of a magnet are the places where the magnetic forces are strongest.

Question 2

What happens when two magnets are brought close together?

Answer 2

They exert a force on each other.

Question 3

Two like poles…

Answer 3

…repel each other.

Question 4

Two ______ poles attract each other.

Answer 4

unlike

Question 5

The attraction and repulsion between two magnetic poles is an example of what?

Answer 5

A non-contact force.

Question 6

Which direction do magnetic field lines go?

Answer 6

From the north (seeking) pole of a magnet to the south (seeking) pole of a magnet.

Question 7

What is a permanent magnet?

Answer 7

A magnet which produces its own magnetic field.

Question 8

What is an induced magnet?

Answer 8

A material that becomes a magnet when it is placed in a magnetic field.

Question 9

What does induced magnetism always cause?

Answer 9

A force of attraction.

Question 10

What happens when an induced magnet is removed from a magnetic field?

Answer 10

It loses most/all of its magnetism quickly.

Question 11

What is a magnetic material?

Answer 11

Any material or object that can be influenced by a magnetic
field, and has the potential to become a magnet.

Question 12

What is a magnetic field?

Answer 12

The region around a magnet where a force acts on another magnet or on a magnetic material.

Question 13

List the magnetic materials (at room temperature)

Answer 13

Iron
Steel (alloy of iron)
Cobalt
Nickel

Question 14

The force between a magnet and a magnetic material is always one of …

Answer 14

attraction

Question 15

What does the strength of a magnetic field depend on?

Answer 15

The distance from the magnet.

Question 16

Where is a magnetic field the strongest?

Answer 16

At the poles of a magnet.

Question 17

How do we work out the direction of a magnetic field at a particular point?

Answer 17

It is the same as the direction of the force that would act on another north pole placed at that point.

Question 18

Give examples of magnets

Answer 18

Bar magnet
Horseshoe magnet
Earth

Question 19

Does the Earth have a magnetic field?

Answer 19

Yes

Question 20

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

Answer 20

-A magnetic compass contains a small bar magnet

-The north pole of a compass points to the
“top” of the earth.

-The north pole of compass would be
attracted to the south pole of a
bar magnet.

-So, the south pole of the bar magnet inside the Earth is at the geographic north pole and the Earth must have a magnetic field!

Question 21

Describe how to plot the magnetic field pattern of a magnet using a compass.

(1-7)

Answer 21

-Place a bar magnet in the middle of a piece of paper and draw around it

-Mark the north and south poles

-Place a plotting compass at the north pole

-Look at the direction that the pointer is facing

-Mark the tip with a dot

-Move the compass so the tail is on this dot and draw another dot at the tip

-Repeat until back to the magnet at the south pole

Question 22

Explain how you can tell if a magnetic material is a permanent or induced magnet. [2]

Answer 22

Bring it near both poles of a known permanent magnet.

An induced magnetic material will always be attracted by a permanent magnet but a permanent magnet can be both attracted and repelled.

Question 23

Explain why unmagnetised iron is always attracted by a permanent magnet.

Answer 23

The permanent magnet always induces the opposite pole next to its pole, causing the unmagnetised iron to attract.

Question 24

What does a plotting compass contain?

Answer 24

A small bar magnet.

Question 25

Describe how to plot the magnetic field pattern of a magnet using a compass.

(8-10)

Answer 25

-Join the dots and add an arrow to show the direction of the field line

-Repeat from different starting positions around the poles to draw multiple field lines

Question 26

Why is using iron filings not a good way of showing a magnetic field?

Answer 26

They show the shape not the pattern of the magnetic field (i.e. the loops but not the direction).

Question 27

Magnetic objects become
magnetised if placed in…

If _______ from a field, they stop
acting like magnets.

Induced magnets can only be
attracted and

Answer 27

A magnetic field.

Removed

Only permanent or
electromagnets can repel.

Question 28

Things to remember when drawing field lines?

Answer 28

-Field lines never cross

-The closer the field lines, the stronger the field

-Field lines start and end on poles.

-Arrows on field lines go from north to south

Question 29

What is a magnetically soft material?

Answer 29

A material that gains and loses magnetism quickly e.g. iron.

Question 30

What is a magnetically hard material?

Answer 30

A material that gains and loses magnetism slowly e.g. steel.