NEET | 2017Current Electricity and Electrical InstrumentHard

Question

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 :-

Options

A.

R/n

B.

n²R

C.

R/n²

D.

nR

Solution

R = $\frac{ρ l}{A} = \frac{ρ l^{2}}{v o l u m e} \Rightarrow R \propto l^{2}$
$\Rightarrow$ R₂ = n²R₁

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