The resistance of a wire is R. If the length | vedclass

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(B) The resistance of a wire is given by the formula $R = \rho \frac{l}{A}$,where $\rho$ is the resistivity,$l$ is the length,and $A$ is the cross-sec

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$4 R$

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(B) The resistance of a wire is given by the formula $R = ho \frac{l}{A}$,where $ho$ is the resistivity,$l$ is the length,and $A$ is the cross-sectional area.When the wire is stretched to double its length,the new length $l' = 2l$.Since the volume of the wire remains constant,$V = A 	imes l = A' 	imes l'$.Substituting $l' = 2l$,we get $A 	imes l = A' 	imes 2l$,which implies $A' = \frac{A}{2}$.The new resistance $R'$ is given by $R' = ho \frac{l'}{A'} = ho \frac{2l}{A/2} = 4 	imes ho \frac{l}{A} = 4R$.

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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