A step down transformer connected to an AC mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?
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A step down transformer connected to an AC mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?

G1 Physics · Accepted Answer

Step 1: Secondary lamp rating gives Pₛ=44W at 11V, while primary supply is 220V. Step 2: For ideal transformer, input and output powers are equal. Step 3: Primary current Iₚ=Pₚ/Vₚ=44/220=0.2A. Answer A. Final answer: (A) 0.2A.