Question

Determine the expression of the electric field and the electric potential from 0 to infinity along a hollow conductive disk and assuming that a point charge Q is placed in its center. R1 and R2 are the inner and outer radius of the disk respectively.

Answer 1

Given that

• we a hollow conducting disc. So we can say this disc has a considerable thickness and as it's a hollow disc so it will act as a conducting shell.
• A charge Q is placed at the center of the disc

Now coming to the question-

Part first : As we've asked about the electric field along the disc, here there are two possibilities

1. Electric field out of the hollow disc (i.e. shell) = Eout

Eout=KQ/r2

2. Electric field inside the hollow disc =Einside

By using property of conductor we can say the electric field inside the shell is ZERO. Because a hollow conducting body act as an electric shield.

Part 2nd: Electirc potential along the same hollow disc. Again two cases

1. Electric potential out of the shell (Vout)

Very simple Vout= KQ/r

Where r is the distance of any general point from the center of disc.

2. Electric potential inside the shell (Vin)

As it is a hollow conducting disc, so we don’t need to do any work to displace a charge inside the shell, therefore potential will be equal every where inside the shell.

Vin = KQ/R1 .