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A transformer with efficiency 80 % works at 4 kW and 100 V . If the secondary voltage is 200 V , then the primary and secondary currents are respectively

Options

  1. A40   A and 16   A
  2. B16   A and 40   A
  3. C20   A and 90   A
  4. D40   A and 20   A

Correct answer

A. 40   A and 16   A

Step-by-step solution

Here, η = 80 % P i = 4   kW = 4000   W V p = 100   V ,   V s = 200   V I p = P i V p = 4000 100 = 40   A η = V s I s V p I p ; 80 100 = 200 I s 4000 = I s 20 or I s = 20 × 80 100 = 16   A

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