13.1) The picture shows a small compass. The compass needle is free to turn.
It turns to point north-south.
north

a: The compass needle is a small magnet with north and south poles.
Which pole points towards the north?
b: Why does the compass needle turn? Choose the correct explanation from the list below.
• The ends of the compass needle are painted different colours.
• The case of the compass is made of a magnetic material.
• The Earth has a magnetic field.
• The Earth rotates on its axis once each day.
c Describe what you would expect to observe if you turned the compass needle so that it pointed in the opposite direction, and then released it.

13.2) Each of the diagrams, A, B and C below, shows two magnets lying close to each other.

a: For each pair, copy the diagram and add force arrows to show the forces of each magnet on the other.
b: State whether the magnets will attract or repel cach other.

13.3) The diagrams show three electromagnets, A, B and C. Each electromagnet has an electric current of 1 A flowing through it.

a: Explain why B has a stronger magnetic field than A.
b: Explain why C has a stronger magnetic field than A.
c: Describe how you could find out which of the electromagnets, B or C has the strongest magnetic field.

13.4) Umar was investigating magnetic forces. He wanted to find out if the magnetic force of a magnet could pass through iron.

The two pictures show how he investigated this.
paperclip
a: Describe Umar's first observation, as shown in A.
b: Describe Umar's second observation, as shown in B.
c: Write a sentence to state the conclusion Umar would draw from his experiment.
d: State how you would change the experiment to find out if the magnetic force of a magnet can pass through cardboard.