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GCSE Level Questions: Magnets and Electromagnets

Q7. Here is a diagram of an electromagnetic lock used to secure a door. The door unlocks when the switch is closed.

(a) Tick one box to indicate which of the following materials the bolt should be made from

Aluminium  
Brass  
Copper  
Iron  

[1 mark]

(b) Explain why the door unlocks when the switch is closed.

[3 marks]

(c) When the door unlocks, a force of 2.88 N is applied to the spring.

The spring extends by 1.50 cm.

Calculate the spring constant of the spring.

[4 marks]

(d) Give two ways the resultant force on the bolt could be increased.

[2 marks]

(TOTAL 10 marks)