Question:
Space between two concentric conducting spheres of radii $a$ and $b(b>a)$ is filled with a medium of resistivity $p$. The resistance between the two spheres will be :
Correct Option: 1
Solution:
(1) $d R=\frac{(\rho)(d x)}{4 \pi x^{2}}$
$R=\int d R$
$\int d R=\rho \int_{a}^{b} \frac{d x}{4 \pi x^{2}}$
$\Rightarrow R=\frac{\rho}{4 \pi}\left[\frac{-1}{x}\right]_{a}^{b}$
$R=\left(\frac{\rho}{4 \pi}\right) \cdot\left(\frac{1}{a}-\frac{1}{b}\right)$