Question

Question #e36fe

Answer 1

The answer is -3 esu.

First of all, let us assume that hollow sphere is conductive. This implies that there is no electric field out of both spheres (no electric field can go in or out from a conductive body).
According to Gauss theorem:

`int vec E "d" vec s = frac{q}{varepsilon_0}`

If `vec E = 0` out of both spheres, then `q_"total" = 0`. If `q_"inner sphere"= 3 " esu"` then `q_"hollow sphere" = -3 " esu"`.

A further description of the problem involves applying Gauss theorem to calculate electric field, `vec E`, at any point between both spheres, in order to demonstrate that it vanishes at the hollow sphere.