Question

A solid copper sphere has a net positive charge. The charge is distributed uniformly over the surface of the sphere, and the electric field inside the sphere is zero. Then a negative point charge outside the sphere is brought close to the surface of the sphere. Is all the net charge on the sphere still on its surface? If so, is this charge still distributed uniformly over the surface? If it is not uniform, how is it distributed? Is the electric field inside the sphere still zero? In each case justify your answers.

Short answer

Yes, all the net charge on the sphere still on the surface. No, it is not distributed uniformly over the surface. Yes, the electric field inside the sphere is still zero.

Step-by-step solution

Charge on the sphere will not change

For the first part of the question, yes, the charge on the sphere will not change and still will apply an electric field on the point charge outside the sphere.

We, know that the outside pointing charge will apply an electric field on the positive charge on the surface and pull the positive charge towards itself, hence the charges are not distributed equally.

Electric field inside the sphere is zero.

The distribution of the positive charge is shown below in the diagram. The positive charges will be that side where the negative charge faces outside the sphere.

Since, all the charges are on the surface even at the application of an electric field, the electric field inside the sphere is zero.