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(B) The resistance of a wire is given by $R = ho \frac{l}{A}$.When a wire is stretched,its volume $V = l 	imes A$ remains constant.If the length $l

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$4 R$

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(B) The resistance of a wire is given by $R = ho \frac{l}{A}$.When a wire is stretched,its volume $V = l 	imes A$ remains constant.If the length $l$ is doubled $(l' = 2l)$,the area of cross-section $A$ becomes half $(A' = A/2)$ to keep the volume constant.The new resistance $R'$ is given by $R' = ho \frac{l'}{A'} = ho \frac{2l}{A/2} = 4 	imes ho \frac{l}{A} = 4R$.Therefore,the new resistance is $4R$.

The resistance of a wire is $R$. If the length of the wire is doubled by stretching,then the new resistance will be

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