Question

A charge Q is uniformly distributed on a spherical shell. What is the field at the centre of the shell? If a point charge is brought close to the shell, will the field at the centre change? Does your answer depend on whether the shell is conducting or non-conducting?

Answer 1

The answer does not depend on whether the shell is conducting or non-conducting.

Explanation:

• In the absence of the external field, the field intensity is going to be zero even if it is a non-conducting shell. Just consider an image in which a shell has opposite points.
• The charge at those points is equal and from those points, the displacement vectors to the center are equal and opposite in magnitude.
• Due to diametrically opposite points, the electric field will cancel out. But if there is an external electromagnetic/electric field and there will be no charges to be rearranged in the conducting shell. Inside the shell, the field intensity at all the points will be zero.