Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Jump In The Capacitor Voltage?

  1. Oct 11, 2008 #1
    I know that voltage of a capacitor is continuous. However, I want to learn that; can it be a jump in the capacitor voltage? Also, if it is, how it can be happened?
  2. jcsd
  3. Oct 11, 2008 #2


    User Avatar
    Science Advisor

    Classically, to charge a capacitor requires current. To charge a capacitor in zero time requires infinite current, which is not possible. I could imagine that if the charging were very fast, it might be reasonable to approximate it as an instantaneous jump in voltage.

    But charge is quantized. I wonder what happens in the quantum mechanical case. :confused:
  4. Oct 12, 2008 #3
    charge on a capacitor is given by q = CV....there is superficially no time here ....BUT

    atyy's explanation is a good one: charge is the result of the flow of electrons which have have finite, not instantaneous speed....in fact charge in coulombs is given by q=it...amps times time....so in this formulation you can see...charging takes some "t".....

    in fact a step function (square wave) voltage will charge it really,really,fast.....but not instantaneously...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook