Capacitor charging with unknown resistor

[cdotter]

Homework Statement

Capacitor voltage as a function of time is recorded for a simple direct current RC series charging capacitor. How could we determine the resistance of the resistor?

Homework Equations

$$q=Qe^\frac{-t}{RC}$$

The Attempt at a Solution

I understand the question I'm just having trouble figuring it out.

If I know the voltage at a certain time t, couldn't I say that q=Cv? Then

$$Cv=Qe^\frac{-t}{RC} \Rightarrow R=\frac{-t}{C\;ln(\frac{Cv}{Q})}$$

Where Q=CV and V=the voltage of the capacitor after it's finished charging?

Or is q=Cv incorrect?

 

[cdotter]

Anyone?

 

[chaoseverlasting]

That would work. Another way is to differentiate the equation wrt time to get current and to measure current at different points in time. From those values too you can find the resistance. I think this principle is used in measurement of resistances using the Anderson (?) Bridge. I might be thinking of another bridge though.

 

[cdotter]

I didn't think of that. Thank you.