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GCSE Level Questions: Magnets and Electromagnets

Q4. The diagram shows a solenoid.

(a) Draw the magnetic field of the solenoid onto the diagram.

[2 marks]

(b) This diagram shows two iron rods placed inside a solenoid:

 

Explain why the iron rods move apart when the switch is closed.

[2 marks]

(c) Ross investigated the strength of an electromagnet. He was instructed to investigate how the strength depended on:

the current in the wire

the number of turns of wire around the iron core.

Here is the equipment he used

Ross measured the strength of the electromagnet by finding the maximum weight the electromagnet could hold.

The table below shows his results.

Current in amps
Number of turns of wire
Maximum weight held/ N
1.0
30
6.5
1.5
20
6.4
2.0
10
3.7

 

Explain why the method used by the student is not valid for this investigation.

[2 marks]

(d) Chandler used the same equipment to perform his investigation.

Here are Chandler's results displayed on a graph:

(i) How does increasing the current in the wire affect the strength of the electromagnet, when the electromagnet has 30 turns of wire?

[1 mark]

(ii) How does increasing the number of turns of wire from 10 to 20 affect the strength of the electromagnet, compared to increasing the number of turns of wire from 20 to 30?

[1 mark]

(TOTAL 14 marks)