Hi, I have a question. Electric current in the circuit according to the relation I=1-10cos(50t). Determine the time when the Q=0 C. I used: I =dQ/dt Q(t) = ∫ Idt = ∫(1-10cos(50t))dt = t - (10/50)sin(50t) + C = t - 0.2sin(50t) + C But what now ? I donť known how can i calculate the time... Someone told me that i must find the interval of definite integral... from t=0 to t=?.... Thank you for reply.