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NTA Abhyas JEE Main2020PhysicsAlternating CurrentPractice

A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the current is 0 . 5 A , the efficiency of the transformer is

Options

  1. A86%
  2. B91%
  3. C96%
  4. D98%

Correct answer

B. 91%

Step-by-step solution

Given: Output power, P = 100 W The voltage across the primary coil, V p = 220 V Current in the primary coil, I p = 0 . 5 A The efficiency of a transformer, η = output power input power × 1 0 0 = P V p I p × 100 = 100 220 × 0.5 × 100 ≈ 91 %

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