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: Energy Stored on a Capacitor

  1. May 5, 2008 #1
    1. The problem statement, all variables and given/known data
    Q18. A 20 F capacitor is charged to 200 V. Its stored energy is:
    C. 0.4 J


    2. Relevant equations
    q = CV
    u = .5CV^2


    3. The attempt at a solution
    I tried plugging in the numbers and got 1.6E6, which isn't even close to the answer. I really don't know where to go with this one. I even went and found an energy calculator online and it came up with the same answer I got. Is stored energy not the potential energy of the capacitor?
     
  2. jcsd
  3. May 5, 2008 #2

    alphysicist

    User Avatar
    Homework Helper

    Hi Strawberry,

    Are you sure the capacitance wasn't [itex]20 \mbox{ }\mu F[/itex]? Most capacitors that I've dealt with in problems are in that range, and that would also give the answer you are given.
     
  4. May 5, 2008 #3
    I guess the symbol just didn't show up in the .pdf. Thanks again alphysicist, you've cleared up a ton of things for me in the past few weeks.
     
  5. May 6, 2008 #4

    alphysicist

    User Avatar
    Homework Helper

    Sure, I'm glad I could help!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook