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In a step-down transformer with 1000:100 turn ratio (primary:secondary), 220 V input, 1 A secondary current. Primary current (ideal):
A0.1 A
B1 A
C100 A
D10 A
Answer & Solution
Correct answer: A. 0.1 A
V₁I₁ = V₂I₂ for ideal transformer. V₂ = 220 × (100/1000) = 22 V. I₁ = (V₂I₂)/V₁ = (22 × 1)/220 = 0.1 A. (Or: I₁/I₂ = N₂/N₁ = 1/10.)
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