STANDARDPhysics-Electromagnetic Induction
STANDARD Physics Transformers MCQ Question
Type: MCQ-numerical-Medium-Class 12
A transformer is used to light 140 W, 24 V lamp from a 240 V ac mains. If the main current is 0.7 A, the efficiency of the transformer is
A
63.8%
B
74%
C
83.3%
D
48%
Correct Answer
Option C
Detailed Explanation
Output power = 140 W. Input power = 240 × 0.7 = 168 W. Efficiency = (output power / input power) × 100 = (140 / 168) × 100 = 83.3%.
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