Answer to Question #289818 in Electricity and Magnetism for Chemistry

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.

Answer 1

The following is the schematic diagram of the charge having a positive charge.

When a solid copper sphere has a positive charge, which is divided consistently on the sphere's surface, having zero electric fields inside it, there is the net charge on the sphere's surface because the charge on the sphere's surface will not vary. Also, an electric field is applied to the charge placed outside.

The charge is not divided over the sphere's surface because the point charge outside the sphere will exert an electric field on the sphere's surface's positive charge. Also, it will try to pull the positive charge.

The distribution of the charge is shown below:

As shown in the above diagram, the positive charges will be scattered consistently on the sphere's side, where the negative charge is located outside the sphere.

Inside the sphere, the electric field is still zero because even after applying the electric field, all the positive charges are on the sphere's surface. So, there is no charge within the sphere.

Thus, the electric field inside the sphere is still zero.