KS3: Magnetism Questions
Q4. The diagram shows a wire wrapped around a box to form a rectangular coil and circuit. The coil has two iron rods in it. The rods are parallel and touching. They are free to move.
(a) When the switch is closed, the two rods move apart.
(i) Explain why this happens.
The current in the coil produces a magnetic field or 'the current produces a magnetic field' or 'the coil produces a magnetic field' or 'the coil becomes an electromagnet' 
The rods are both magnetised in the same direction so that the N or S poles are next to each other'.
The rods repel each other and roll apart.
3 marks
(ii) The switch is then opened to break the circuit. What, if anything, happens to the two iron rods?
Nothing or they stay where they are
or 'they become demagnetised'
1 mark
(b) One of the two iron rods is taken out and replaced with a brass rod.
The rods are parallel and touching.
What, if anything, will happen to the rods when the switch is closed?
Explain your answer.
Nothing happens because only the iron rod becomes magnetised or because the brass rod does not become magnetised.
2 marks
(Total 6 marks)
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