1. The problem statement, all variables and given/known data The time for which the diode conducts is 2. Relevant equations Using integration and differentiation Vc = 1 / C integral (current)(dt) 3. The attempt at a solution Vs = -Vc Vm sin(wt) = -Vc = - (1/C) integral (Idt) now differentiate both sides to get expression for I that is current. Vm (coswt) * w = -(1/C) I So I = Vm(costwt) * C * w (-1) So now i draw current wave, and then how to proceed? How do you get an answer for this? Am i to find out when current goes negative? There was a similar question for RL circuit that was Vs = L di/dt so integrate to get expression for current. Vs sin(wt) = L di/dt Vs sin (wt) dt = L di integrating Vs cos (wt) (-1) / w + k = L * I I = Vs cos (wt) (-1) /(wL) + k' where k' = k/L equation 1 to find value of K' take initial condition. At t = 0, I = 0 so 0 = Vs (1) (-1) / (wL) + k' from equation 1 K' = Vs/(wL) equation 2 so expression for current becomes from equation 1 and 2 I = Vs cos(wt) (-1) / (wL) + Vs / (wL) = Vs/ (wL) * (1 - cos (wt)) Drawing this we get I is always positive, so it conducts for 360 degrees when input goes 1 entire cycle. 360 degrees was right for RL circuit but for RC answer is not given as the book is old and the page is torn. i'm not sure what to do in case of given question of diode + C with charged as shown. Expression is I = Vm(costwt) * C * w (-1) So what to now?