Apr 7, 2017
We need to understand a few things about charged conductors.
- In electrostatic equilibrium free charges in a good conductor reside only on its surface.
Consider a conductor with excess of electrons. These excess electrons repel each other, as like charges repel. Consequently these move to the surface of the conductor.
- The charges distribute on surface of conductor so that the electric field inside the conductor is zero. If the field wasn't zero, any free charge would need to move under the influence of electric field.
- The electric field at the surface of the conductor is perpendicular to the surface. If it wasn't so, there would exit a component of the electric field along the surface. Any free charge under influence of this component of electric field would move along the surface.
This is inconsistent with the charges on the conductor being in equilibrium.
- Charge accumulates, and therefore field is strongest, on pointed parts of the conductor.
This happens as so balance the forces on each charge.