Space between two concentric conducting spheres of radii a and b ( b > a ) is filled with a medium of resistivity ρ . The resistance between the two spheres will be:

Step-by-step solution

Consider small volume element between r and r + d r Resistance of this volume along rational directions, d R = ρ d r 4 π r 2 As all element resistance are in series, R = ∫ r = a r = b ρ d r 4 π r 2 = ρ 4 π - 1 r r = a r = b = ρ 4 π 1 a - 1 b