1. Not finding help here? Sign up for a free 30min 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!

Finding the potential difference?

  1. Mar 24, 2007 #1
    okey the question goes like this

    A plate capacitor with area A and distance d1 is charged to a potential difference of V1 between the plates. Now the distance between the plates increases to d2 = 2*d1.

    a) What is the new potential difference, V2, between the plates?

    b) Find the increase in stored energy, deltaU, an explain where this energy comes frome.

    what I have found out so far is:
    a) V2 = E*2*d1, where E = Q/(e0*A) and therefore does not change with distance.

    b) deltaU = 1/2*Q*V2 - 1/2*Q*V1

    I don't think these two answers are good enough, but I can't se what else to do, maybe use intgral?
    any help is highly appreciated:smile:

    Kind regards

  2. jcsd
  3. Mar 24, 2007 #2

    using your eqn a) what is the ratio v2/v1?
  4. Mar 24, 2007 #3
    well the ratio must be V2/V1 = d1, but this can't be the answer to a) could it?
  5. Mar 24, 2007 #4
    unless I miss my guess, it should be 2di/di=2.
  6. Mar 25, 2007 #5
    hehe yea ofcorse:smile:
    but I still don't think the ration is the answer to thequstion, thanks though:smile:
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Finding the potential difference?