Having a bit of trouble with this question; I'm asked to calculate the time in ms it takes to dissipate 40% of the initial stored energy of an Inductor.I know that the initial stored energy is 62.5 JThe time constant is 50msV 200e^(-20t)I 12.5e^(-20t)I've worted out the above values, but I cannot see how I can work out the time taken for it to discharge 40%, as i keep getting a negative time value.I would be very grateful of any help :)(P.S. I also need the same for a capacitor when I have similar values)
0.4 e^(-20t) ln(0.4) -20t t ln(0.4)/(-20) t (-0.916)/(-20) t 0.0458 46ms
