# Jump In The Capacitor Voltage?

1. Oct 11, 2008

### symsane

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. Oct 11, 2008

### atyy

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.

3. Oct 12, 2008

### Naty1

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...