Subject: capacitor discharge rate
I'm need my math checked! I need to be solve for t in the following rate problem for an electrical capacitor. Vr = E(e^-t/RC), e=nat. log 2.718 raised to the -t/RC power. Every time I do this it comes out different. Thanks for your time.
Bill Phillips teacher of ScienceHi Bill,
With Vr = E e-t/RC I would first divide both sides by E and then take the natural log. Thus
Vr /E = e-t/RC
ln(Vr /E) = -t/RC
t = -RC ln(Vr /E)
There are different ways you can write this which is maybe why you got different answers.
t = -RC (lnVr - ln E)
t = RC (ln E - lnVr)
t = RC (ln E /Vr)