Space between two concentric conducting spheres of radii a and \(b (b > a)\) is filled with a medium of resistivity \(\rho\). The resistance between the two spheres will be :
1
\(\dfrac{\rho}{4 \pi} \left(\dfrac{1}{a} - \dfrac{1}{b} \right)\)
2
\(\dfrac{\rho}{2 \pi} \left(\dfrac{1}{a} - \dfrac{1}{b} \right)\)
3
\(\dfrac{\rho}{2 \pi} \left(\dfrac{1}{a} + \dfrac{1}{b} \right)\)
4
\(\dfrac{\rho}{4 \pi} \left(\dfrac{1}{a} + \dfrac{1}{b} \right)\)