Q. If the resistivity of the potentiometer wire is $\rho$ and area of cross section $A$, the potential gradient along the wire will be ( $I$ is the current )

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A

$I \rho / A$

B

$I / A \rho$

C

$I A / \rho$

D

$I a \rho$

Solution:

Pot. gradient
$V / L=I R / L=[I / L] \times[\rho L / A]$
Therefore $V / L=I \rho / A$

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