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IGCSE · 4 · multiple choice

Electricity and magnetism · Question 6

Electricity and magnetism · Original GioPhysics question with a detailed, mark-by-mark answer guide.

Demand
routine
Marks
1
Topics
1
Answer
Complete
Transformer with a 200-turn primary and a 5000-turn secondary on an iron coreiron coreprimary coil200 turns12 V a.c.secondary coil5000 turnsoutput
Fig. 6.1A transformer drawn as a rectangular iron core with a hollow centre. Wound around the left limb is the primary coil, labelled 200 turns and drawn as five loops encircling the limb; its two ends run out to the left to a 12 V a.c. supply, drawn as a circle containing one cycle of a sine wave. Wound around the right limb is the secondary coil, labelled 5000 turns and drawn as seven closer-spaced loops; its two ends run out to the right to a pair of open output terminals.
multiple choice1 mark

A transformer has 200 turns on the primary coil and 5000 turns on the secondary coil. The primary is connected to a 12 V a.c. supply. What is the output voltage?

  1. A

    0.48 V

  2. B

    12 V

  3. C

    300 V

  4. D

    1200 V

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Answer overviewCorrect answer: C — 300 V
01

Answer and reasoning

1 mark
How to approach it

Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.

  1. 1

    The correct choice is C: 300 V

  2. 2

    A inverts the turns ratio. With more turns on the secondary this is a step-up transformer, so any answer at or below 12 V can be discarded before the arithmetic.

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