# Charged soap bubble problem

1. May 10, 2012

### Pandabasher

1. The problem statement, all variables and given/known data
A soap bubble of radius 0.1mm has a wall thickness of 3.3x10^-8m, and is charged to a potential of 100V. Give a formula for the charge of the bubble.

I know this is probably a really easy question, but I've only ever done problems with spheres of negligible wall thickness, so not sure if the wall makes a difference.
I know the equation for potential, so I could just rearrange that to get get Q.

Any help is appreciated, cheers.

2. May 10, 2012

### rude man

Some malicious profs have a tendency to give you irrelevant data. Did you know that?

Real question is: what is the outside radius? Is it 0.1mm or 0.1mm + 3.3e-8m? The problem as stated doesn't say, but you'll have to make an assumption. Of course, 3.3e-8 << 1e-4.

3. May 10, 2012

### Pandabasher

I think the point is that the thickness IS negligible as you say, so I've been trolled by Professor after all, haha. Thanks.