1. The problem statement, all variables and given/known data The voltage across the capacitor is 10V when t<0 The switch is closed at t=0 I have to find the diff eq. in terms of Vs, C, R by balancing the current at node Vc(t). But i am not sure whether the Vs is 0 or 10V at t<0 3. The attempt at a solution I am assuming Vs = 0 at t<0 since the voltage across capacitor is 10V. Also, I am not sure what current balance at the node means...I mean when the switch is closed the current through the capacitor is the same as current through the resistor. So, iR = iC (Vc/R) = C (dVc/dt) How do i write this in term of Vs? Isn't the current through the resistor Vc/R since Vs is 0 at the beginning?