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: Electric field outside of a cavity

  1. Jul 10, 2015 #1
    1. The problem statement, all variables and given/known data

    Hi everyone. I m just studying capacitors but I have problems with gauss law. In one exercise it says that we have a sphere(cavity) of radius r, with a charge q placed inside the sphere of it. Wie have to find the electric field inside and outside sphere.
    The solution says: inside the sphere the electric field is q/4πeor^2,Outside of it the field is 0.
    The thing I don't understand, why is the field 0?shouldn't we have a distribution of charge for which inside the sphere we have a charge -q, so the net field is 0,then on the surface we have a charge +q that gives an electric field,(q/4πr^2),similar to that of a point-like charge??? Please help me

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jul 10, 2015 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Is this a cavity within a conductor, and you are asking about the field outside the cavity but still within the conductor? If not, please provide details exactly as stated in your referenced text.
  4. Jul 10, 2015 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    I think you mean inside the cavity, and outside the cavity but still inside the sphere.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted