Q21 · 2021 · Paper 1Simple familiar3 marks
QUESTION 21 (3 marks)
Explain how transformers work in terms of Faraday’s law and electromagnetic induction.
WORKED SOLUTION
3 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
Alternating current passing through the first coil creates a
magnetic flux. This magnetic flux induces an EMF in the
secondary coil. The induced EMF is proportional to the
number of coils and the rate of change of the magnetic flux.
• recognises that alternating current creates a
changing magnetic flux [1 mark]
• recognises that EMF is induced in the second
coil by the changing magnetic flux in the first coil
[1 mark]
• identifies that the induced EMF is proportional to
the number of coils and the rate of change of
magnetic flux [1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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