# Homework Help: EM Problem: Floating Conducting Cylinder

1. Feb 16, 2013

### jegues

1. The problem statement, all variables and given/known data

See figure attached.

2. Relevant equations

3. The attempt at a solution

Originally I have solved this problem using Gauss's law by defining a gaussian surface in the form of a cylinder around the floating cylinder to get the electric field distribution underneath the cylinder to ground.

The result I obtained was,

$$V(y) = \frac{Q_{pul}}{4 \pi \epsilon_{0}}\left( \frac{ln(d-y)}{d} \right)$$

but since we aren't told what Qpul is we cannot plot the variation of the voltage.

My professor suggested I try solving this problem using image theory and laplaces equation in cylindrical coordinates in order to avoid Qpul.

Can someone explain to me how this done?

Thanks again!

#### Attached Files:

• ###### EMQ.jpg
File size:
17 KB
Views:
85
2. Feb 18, 2013