MHT CET · Physics · Current Electricity

A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the ratio of output to input power is 0.8, then the current drawn by primary winding is

A 3.6 A
B 5.0 A
C 2.5 A
D 2.8 A

Verified Solution

Answer & Solution

Correct Answer

(B) 5.0 A

Step-by-step Solution

Detailed explanation

Given, input voltage supplied to transformer,

V_{1} = 220 V

Current at output circuit of transformer,

i_{2} = 220 V

V_{2} = 440 V

\frac{o u t p u t p o w e r (P_{2})}{I n p u t P o w e r (P_{1})} = 0.8 \Rightarrow \frac{V_{2} i_{2}}{V_{1} i_{1}} = 0.8

\frac{440 \times 2}{220 \times i_{1}} = 0.8 \Rightarrow i_{1} = \frac{4}{0.8} = 5 A

Hence, current drawn by the primary windings is 5 A.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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