A sperical ballon od radius R charged uniformly on its surface with surface density `sigma`. Find work done against electric forces in expanding it upto radius 2R.

A flat disc of radius R charged uniformly on its surface at a surface charge density sigma . About its central axis of rotation it rotates at an angular speed omega . Find the magnetic moment of disc due to rotation of charges.

A spherical shell of radius b with charge Q is expanded to a radius a. Find the work done by the electrical forces in the process.

A sperical shell of radius R with uniform charge q is expanded to a radius 2R. Find the work perfomed by the electric forces and external agent against electric forces in this process.

A sperical shell of radius R with uniform charge q is expanded to a radius 2R. Find the work perfomed by the electric forces and external agent against electric forces in this process.

A uniform disc of radius R is charged with a uniform surface charge density sigma . Find the electric potential due to the charges on the disc at a point on its edge. [(sigmaR)/(piin_(0))]

A spherical shell of radius R_(1) with uniform charge q is expanded to a radius R_(2) . Find the work performed by the electric forces in this process.

A spherical shell of radius R_(1) with uniform charge q is expanded to a radius R_(2) . Find the work performed by the electric forces in this process.

A spherical shell of radius R is uniformly charged to a surface charge density sigma . Br State the theorem which can be used to find the electric field outside the shell.