The resistance of a wire is ‘ R ’ ohm. If it is melted and stretched to ‘ n ’ times its original length, its new resistance will be: - Physics MCQ NEET (UG) 2017 2026 | ExamTest.live

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The resistance of a wire is ‘ R ’ ohm. If it is melted and stretched to ‘ n ’ times its original length, its new resistance will be:

Solution & Step-by-step Explanation

When a wire is stretched, its volume V = A l remains constant.Resistance R = ρ \frac{l}{A} .Since A = V / l, R = ρ \frac{l ^{2}}{V} .Thus, R \propto l^{2} .If l^{'} = n l, then R^{'} = n^{2} R .

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The resistance of a wire is ‘ R ’ ohm. If it is melted and stretched to ‘ n ’ times its original length, its new resistance will be:

n R

n^{2} R

\frac{R}{n ^{2}}

\frac{R}{n}

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