A cylindrical conductor of length


A cylindrical conductor of length l and uniform area of cross-section A has resistance R. Another conductor of length 2l and resistance R of the same

material has area of cross-section.

(a) A/2

(b) 3A/2

(c) 2A

(d) 3A



Explanation : $\mathrm{R}=\rho \frac{l}{\mathrm{~A}}$  $\ldots(i)$

Also  $\mathrm{R}=\frac{\rho(2 l)}{\mathrm{A}^{\prime}}$ $\ldots(i i)$

From eqns. $(i)$ and $(i i)$ 

$\frac{1}{\mathrm{~A}}=\frac{2}{\mathrm{~A}^{\prime}}$ or $\mathrm{A}^{\prime}=2 \mathrm{~A}$

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