Q262 · Practice questionSimple familiar4 marks
QUESTION 262 (4 marks)
An ideal transformer has primary turns and secondary turns. Its primary is connected to a rms AC supply.
a)[3 marks]
Explain how an EMF is induced in the electrically isolated secondary coil.
b)[1 mark]
Calculate the secondary rms voltage.
WORKED SOLUTION
4 marksPractice marking scheme
ANSWER
(a) Alternating primary current creates changing magnetic flux in the common core; the changing flux links the secondary and induces an EMF by Faraday extquotesingle s law. (b) .
Worked solution
(a) The coils do not need electrical contact. Energy transfer occurs through their shared changing magnetic field. Secondary EMF depends on the rate of change of flux linkage.
(b) .
Equivalent physically justified methods, alternative valid sketches and consistent units accepted.
Accept sensible significant figures and consistent rounding from stated constants.
Part a: Link alternating primary current to changing magnetic flux.
Part a: State that this flux links the secondary via the core.
Part a: Use Faraday law to explain the induced secondary EMF.
Part b: Calculate the secondary voltage using the turns ratio.
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
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