1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Charged soap bubble problem

  1. May 10, 2012 #1
    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. jcsd
  3. May 10, 2012 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

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

    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.
  4. May 10, 2012 #3
    I think the point is that the thickness IS negligible as you say, so I've been trolled by Professor after all, haha. Thanks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook