# Capacitor Equations

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1. Jun 17, 2017

### ace8888

1. The problem statement, all variables and given/known data
Hi, i've run into two different equations for the voltage of a typical RC circuit, one resistor, and one capacitor.
Please explain the different between the two. One has a 1 - the natural log and the other one doesnt.

2. Relevant equations
1. V(t) = Vo*e^(-t/RC)

2. Vc = Vs(1-e^-t/RC)

3. The attempt at a solution

2. Jun 17, 2017

### kuruman

One of the equations is for a charging capacitor and the other for a discharging capacitor. To figure out which is which, evaluate each expression at t = 0 and at t → ∞ .

3. Jun 17, 2017

### ace8888

thanks!

4. Jun 18, 2017

### haruspex

It is not a log; it is a negative exponential.
Do you understand what these two curves look like?

5. Jun 18, 2017

### ace8888

Typo, yes it is the natural exponent. I dont know why but i was thinking exponent and typed log. They are inverse of each other.

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