1. The problem statement, all variables and given/known data I have an RC circuit where C = 0.4 * 10^-6, R = 50k Ohms. The problem says: "Find the length of time required to dissipate 75% of the initially stored energy." 2. Relevant equations energy 1: 1/2 * C * v(t) energy 2) w = ∫p(t)dx, from 0 to t 3. The attempt at a solution This is the last part of the problem. I solved everything else up to this point correctly. v(0) = 200 V, Tau = 0.02s. The initial energy stored in the capacitor is 8mJ. Now I set p(t) = v(t) / R, and integrate from 0 to t. That gives me the expression for the energy, which I then set equal to 0.25 * w(0) = 2 * 10^-3 J. However this gives me that t = 2.877ms, which is wrong according to the solutions manual. It uses the first energy formula and gets t = 13.86ms. Can someone explain why these two formulas give two different answers, or point out any mistake I have done.