We know that voltage across a capacitor is given by

But there is this other formula

How this second formula was deducted mathematically from the first one? or from another one?

• in the second formula, what is R, $V_s$ and $V_c$? You need to explain it to us – FrancoVS Jun 26 '18 at 11:18
• @FrancoVS - Vc should be voltage on capacitor. Vs will be the source voltage. – Whiskeyjack Jun 26 '18 at 11:29
• Do you know how to solve an ODE? – Spehro Pefhany Jun 26 '18 at 11:31