A metal ball of radius `a` is surrounded by a thin concentric metal shell of radius `b`. The space between these electrodes is filled up with a poorly conducting homogenous medium of resistivity `rho`. Find the resistance of the interelectrode gap. Analyse the obtained solution at `b rarr oo`.

There are two concentric spheres of radius a and b respectively. If the space between them is filled with medium of resistivity rho , then the resistance of the intergap between the two spheres will be (Assume bgta )

A metal ball of radius a is located at a distance l from an indinite ideally conducting plane. The space around the ball is filled with a homongeous poorly conducting medium with resistivity rho . In the case of a lt lt l find : (a) the current density at the conducting plane as a function of distance r from the ball if the potentail difference between the ball and the plane is equal to V , (b) the electric resistance of the medium between the balll and the plane.

Two metal balls of the same radius a are located in a homongenous poorly conducting medium with resistivity rho . Find the resistance of the medium between the balls provided that the separation between them is mush greater than the radius of the ball.

A sphercial capacitor is made of two conducting spherical shells of radii a and b.The space between the shells is filled with a dielectric constant K up to a radius c as shown in figure. Calculate the capacitance .

A solid conducting sphere of radius R is surrounded by a concentric metallic shell of inner radius 2R and outer radius 3R. The shell is earthed. The inner sphere is connected to a switch S by a thin conducting wire through a small hole in the shell. By closing the switch S, the inner sphere is connected to a distant conducting sphere of radius R having charge Q. Find the charge that flows to earth through wire AB.

A uniform metal sphere of radius R and mass m is surrounded by a thin uniform spherical shell of same mass and radius 4R . The centre of the shell C falls on the surface of the inner sphere. Find the gravitational fields at points A and B .

A hollow metallic sphere of radius 20cm surrounds a concentric metallic sphere of radius 5cm. The space between the two sphere is filled with a nonmetallic material. The inner and outer sphere are maintained at 50^(@)C and 10^(@)C respectively and it is found that 100J of heat passes from the inner sphere to the outer sphere per second. Find the thermal conductivity of the material between the sphere.