Question

4.If, for a given conductor, the local surface charge density is sigma, what is the direction and magnitude of the electric field in that region?

What’s the value of the electric field inside a conductor and why?

Where is the excess stationary electric charge located for a conductor and why?

Answer 1

4-

The magnitude of the electric field in the region of a charged conductor is given by. The direction of

is at right angles to the surface pointing away from the surface if the charge is positive. This can be found by applying Gauss's law to a hypothetical "pill box" of cross section A as a Gaussian surface.

B-

The value of the electric field inside the conductor is zero as all the charge on a conductor settles on its surface so that there is no charge inside the conductor. Therefore by applying Gauss's law to a surface just inside the surface of the conductor we obtain the above result.

C -

All the excess stationary charge on a conductor settles on its surface as when electrostatic equilibrium is reached the electric fields inside the conductor are zero. Thus from Gauss's law the result follows.