"We will concentrate on the time taken for the capacitor to discharge to exactly one-half of its p.d, and how this varies with the value of the resistor. So repeat the experiment with different recorded values of R, and find the corresponding T, the time taken for V to fall from 9 V to 4.5 V (for example). Plot T versus R.
Theory suggests that T versus R should be a straight line through the origin with slope C ln 2. Confirm this."
C= Q/V and tau = RC
The Attempt at a Solution
We were using resistors of 4.7 kilo ohms and we we kept adding one more resistor in series every time. After charging the 100 microFarads capacitor we connected it to the resistors and started the stopwatch in order to record the time for the voltage across it to fall to half it's value.
After we did this with about 5-6 different resistances and plotted our data, T vs. R, it wasn't a straight line through the origin. Why is that the case? We did the same experiment 3 times to confirm but each time our results didn't give us a straight line through the origin.
One more difficulty we faced was the potential difference didn't fall to exactly half its p.d for all the resistances.