# Capacity of a Capacitor

1. Feb 16, 2006

### jdog6

This is for a lab I have done and I am stuck on this,

Question : Plot a curve of In (1 - V/Vo) vs time and calculate C from the slope of the line.

Initial equation = V = Vo(1-e^-t/RC)
Calculated Linear Equation : In (1 - V/Vo) = -t/RC
Therefore from y = mx + b = m = -t/RC (i think)
Then, C = -t/Rm

m = -72.673
R = 10 000 ohms
C = what we are looking for
-t = ????? do i use any of my times

Also, C (accepted value) = 6000x10^-6 Farad
Therefore, answer should be near this.

Please help me out! I'm totally stumped. Thank you.

Last edited: Feb 16, 2006
2. Feb 16, 2006

### jdog6

Can anybody help?

3. Feb 16, 2006

### jdog6

i beleive i have a lead t = time constant but i dont know what that is...

4. Feb 17, 2006

### Integral

Staff Emeritus
Yes you must plot all of your data. At each time, t, you measured some voltage, v,. Plot the points t, and

$$\ln ( 1 - \frac v v_0 )$$

where v is your measured values. You should get something linear, find the slope of the line.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook