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: Charge distribution between two spherical hollow conductors.

  1. Apr 12, 2014 #1
    Consider two spherical hollow conductors, charged to Q1 and Q2 coulombs respectively. What happens when one is placed within the other, and they are connected by a thin metallic wire?
    I do know that if they were placed at a distance from each other, the charge is distributed in the ratio of the ratio of their capacitance. The solution to this problem is that all the charge flows from the inner conductor to the outer one. Why? Any help is appreciated.
  2. jcsd
  3. Apr 12, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF;
    Like charges repel.
    This is why they end up evenly distributed on the surface of a sphere: that's the farthest they can get from each other.

    OK so - imagine that Q1=Q and Q2=0 and Q1 is inside - link the two spheres with a wire and what happens?
  4. Apr 12, 2014 #3
    Thank You!
    I know that charge always lies on the surface of the conductor. If I link the two spheres with a wire, would the charge be evenly distributed between the two spheres (i.e, Q/2 and Q/2), or would all the charge flow to the outer sphere?(i.e, Q1=0 and Q2=Q)
  5. Apr 12, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    That's the question I'm trying to get you to work out the answer to :)

    Do you understand why the charge is always on the surface of a conductor?

    You have to take account that like charges repel - the charges will try to get as far away from each other as they can.

    So what happens when one sphere is inside the other?

    You could think of it like this - the two spheres together with the wire joining them comprise a single solid conductor. Where do the charges on a conductor end up?
  6. Apr 12, 2014 #5
    OH, I got it. Thanks. The charges would flow to the larger sphere. The inner sphere will be left with no charge. Am I right?
    Also, What would happen if the two spheres aren't conductors? Would charge be redistributed at all?
  7. Apr 12, 2014 #6

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    That's right - the charges seek to be as far apart as possible - the way to do that is to entirely occupy the outer sphere.

    Strictly: charges flow between the spheres until the net unbalanced charge is evenly distributed across the outer surface of the outer sphere.

    Insulators, by definition, do not conduct charges.
    Therefore the charges don't move - they want to, but the material of the insulator won't let them.

    In practice the situation is messier but you'll learn more about that later in your course.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted