If a wire is stretched to make it 0.1 % longe | vedclass

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(D) The resistance $R$ of a wire is given by $R = \rho \frac{l}{A}$.Since the volume $V = lA$ remains constant when the wire is stretched,we have $A =

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increase by $0.2 \%$.

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(D) The resistance $R$ of a wire is given by $R = ho \frac{l}{A}$.Since the volume $V = lA$ remains constant when the wire is stretched,we have $A = \frac{V}{l}$.Substituting this into the resistance formula,we get $R = ho \frac{l^2}{V}$.Since $ho$ and $V$ are constant,$R \propto l^2$.For small changes,the percentage change in resistance is given by $\frac{\Delta R}{R} 	imes 100 \approx 2 	imes (\frac{\Delta l}{l} 	imes 100)$.Given that the length increases by $0.1 \%$,we have $\frac{\Delta l}{l} 	imes 100 = 0.1 \%$.Therefore,the percentage change in resistance is $2 	imes 0.1 \% = 0.2 \%$.Since the length increases,the resistance increases by $0.2 \%$.

If a wire is stretched to make it $0.1 \%$ longer,its resistance will.......

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