We had an experiment of charging and dicharging a capacitor in a RC circuit.Our instructor asked us to plot our data in a semilogarithmic paper.Then told us the formula of calculting the slope of such a curve.It was:(adsbygoogle = window.adsbygoogle || []).push({});

[itex] \frac {[the vertical distance between two points measured by a ruler]*2.3}{the distance of two successive ones]*[the difference of the two ponit's independent variables]}[/itex]

then asked us two prove that what is this slope I did the following:

[itex]\frac{log \frac{i_{2}}{i_{1}} *ln{10}}{\Delta t}=\frac{ln{i_{2}}ln{i_{1}}}{\Delta t}[/itex]

And we have [itex] ln{i} = ln{\frac{\Epsilon}{R}}-\frac{t}{RC}[/itex]

So we get that the slope is -1/RC.

But the instructor says this proof is incomplete.What's the problem?Can you tell what quantity does this slope idicate?

thanks

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Slope of a semilog plot

**Physics Forums | Science Articles, Homework Help, Discussion**