# GCSE Level Questions: Magnets and Electromagnets

Q1. The diagram below shows two paper clips hanging from a bar magnet. The paper clips have become magnetised.

(a) Label the north and south poles of both paper clips.

[1 mark]

(b) Sally investigated how the number of turns of wire on an electromagnet affects the strength of the electromagnet.

The diagram above shows the equipment Sally used.

Throughout the investigation she kept the current through the wire constant.

She measured the strength of the electromagnet by counting the number of paper clips the electromagnet could hold.

Explain why it was important that the paper clips were all the same size.

[2 marks]

(c) The table shows Sally's results.

 Number of turns of wire on the electromagnet Number of paper clips held 10 3 20 6 30 9 40 12

Describe the pattern of results shown in the table.

[2 marks]

(d) Sally then used 50 turns of wire on the electromagnet.

The electromagnet picked up 18 paper clips.

This was more paper clips than she had expected.

Which one of the reasons listed below is the most likely cause of this result?

Tick one box.

[1 mark]

 Reason Tick The paper clips used with 50 turns were larger than the others. There were less than 50 turns of wire on the electromagnet. Some of the paper clips were already magnetised.

(e) Sally repeated the measurement for 50 turns of wire three more times.

This gave her four readings: 18, 16, 14, 15

Explain what she should now do with the four results for 50 turns of wire.

[3 marks]

(f) Sally wrote the hypothesis: 'Increasing the current through the wire will make the electromagnet stronger.'

Describe how she should change her initial investigation to test this new hypothesis.

[3 marks]

(TOTAL 12 marks)