- Inside a conductor, electrostatic field is zero
- At the surface of a charged conductor, electrostatic field must be normal to the surface at every point
- The interior of a conductor can have no excess charge in the static situation
- Electrostatic potential is constant throughout the volume of the conductor and has the same value (as inside) on its surface
- Electric field at the surface of a charged conductor
- Electrostatic shielding
A spherical conducting shell of inner radius r1 and outer radius r2 has a charge Q.
(a) A charge q is placed at the centre of the shell. What is the surface charge density on the inner and outer surfaces of the shell?
(b) Is the electric field inside a cavity (with no charge) zero, even if the shell is not spherical, but has any irregular shape? Explain.
A 4 µF capacitor is charged by a 200 V supply. It is then disconnected from the supply, and is connected to another uncharged 2 µF capacitor. How much electrostatic energy of the first capacitor is lost in the form of heat and electromagnetic radiation?
a) Show that the normal component of electrostatic field has a discontinuity from one side of a charged surface to another given by
Where `hatn` is a unit vector normal to the surface at a point and σ is the surface charge density at that point. (The direction of `hatn` is from side 1 to side 2.) Hence show that just outside a conductor, the electric field is σ `hatn/in_0`
(b) Show that the tangential component of electrostatic field is continuous from one side of a charged surface to another.