The current in the primary circuit of a potentiometer is $0.2\, A$. The specific resistance and cross section of the potentiometer wire are $4\times10^{-7}\,ohm$ $metre$ and $8\times10^{-7}\, m^2$ respectively. The potential gradient will be equal to .............. $V/m$
AIEEE 2011, Medium
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Potential gradient $=\frac{\Delta V}{\ell}=\frac{i R}{\ell}=\frac{i \frac{\rho \ell}{A}}{\ell}=\frac{\rho i}{A}$
$=\frac{4 \times 10^{-7} \times 0.2}{8 \times 10^{-7}}$
$=0.1 \mathrm{\,V} / \mathrm{m}$
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