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A nichrome wire of resistance 22 Ω is cut to half its length so that its resistance becomes 11 Ω, and reconnected across the same 220 V supply. What power does it now dissipate?
A550 W
B4400 W
C1100 W
D2200 W
Answer & Solution
Correct answer: B. 4400 W
1. Cutting the wire to half its length halves its resistance, so $R = 11\ \Omega$.
2. Use $P = \dfrac{V^2}{R}$ with $V = 220$ V: $P = \dfrac{(220)^2}{11} = \dfrac{48400}{11}$.
3. $P = 4400$ W.
4. The option 2200 W is the power of the full-length wire, not the halved one, so it is rejected.
_Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 4 "Effects of Electric Current", p.59_
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