A heating coil is labelled 100 W, 220 V. The coil is cut in two equal halves and the two pieces are joined in parallel to the same source. Energy now liberated per second is:
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A heating coil is labelled 100 W, 220 V. The coil is cut in two equal halves and the two pieces are joined in parallel to the same source. Energy now liberated per second is:

G1 Physics · Accepted Answer

Step 1: Original resistance R = V²/P. Each half has resistance R/2. Step 2: Two halves in parallel: R′ = (R/2)/2 = R/4. Step 3: New power P′ = V²/R′ = 4V²/R = 4×100 = 400 W.