O-LevelPhysicsElectricity5054/11 · May/June 2012 · Q141 Mark

A transformer connected to a 240V mains supply is used to light a 24 W lamp. The input current to the transformer is 0.11A and the input voltage is 240 V. The useful output power of the transformer is 24 W. What is the efficiency of the transformer?

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A0.10

B0.91

C1.1

D2.6

✓ Correct answer

B: 0.91

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Topic: Electricity, O-Level Physics (syllabus 5054). Multiple choice, 1 mark.
Source: O-Level Physics, May/June 2012 Paper 1 Variant 1, question 14.

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