# 69 - Electricity Questions Answers

Joshi sir comment

Find potential energy of disc having charge density sigma uniformly distributed on its surface,radius R

Joshi sir comment

Let potential of a disc of radius x is V. For this, see video given below

Now potential energy of this disc with a circular layer of charge

Joshi sir comment

A hollow spherical shell of radius r has a uniform charge density sigma. It is kept in a cube of edge 3r such that the center of the cube coincides with the centre of the shell. The electric flux coming out of a face of the cube is

Sir pls sove

Joshi sir comment

if any issue, inform Sir how to solve? My main problem is how is current flowing between the spheres? Is all the current coming out from one sphere going to the other sphere? Sir can you show with a diagram where exactly all the current is going?  Thank you sir.
Joshi sir comment

Current comes out from the surface of one sphere symmetrically

and enters to the surface of other symmetrically.

Resistance of the medium around one sphere is

A solid conducting sphere of radius R is placed in a uniform electric field E as shown in figure-1.441. Due to electric field non uniform surface charges are induced on the surface of the sphere. Consider a point A on the surface of sphere at a polar angle θ from the direction of electric field as shown in figure. Find the surface density of induced charges at point A in terms of electric field and polar angle θ.

Joshi sir comment

To nullify the electric field inside, the conducting sphere creates a situation in which electric field inside due to charge on sphere would be same as that of given electric field. Now this is the case, which is same as Irodov 3.17.

See the video now