Can someone please tell me if my logic is right regarding the above circuit? I'm trying to find the voltage, v for t > 0 i(t) = i(inf) + (i(0) - i(inf))*exp(-t/(R/L)) At i(0), the current across the 10ohm resistor will be 2 A as the inductor causes the current in its branch to be zero -> current can't change instantaneously. At t(inf), the inductor will be short circuit to steady state dc, so circuit acts like a current divider and the current across the resistor in question will be Ix = (Rt/Rx)*(Is) = (5/10)*2 = 1. so the current flowing throug the resistor in question for t > 0 will be i(t) = 1 + (2 - 1)*exp(-t/20) = 1 + 1*exp(-t/20) thus the voltage will be 10 + 10*exp(-t/20) answer says i'm right, but when i showed my working to my tutor, he didn't know what the hell i was on about.
Vanush, You defined the current source as 2u(t), which means constant 2 amps after t>0. Why do you show it as variable with time? Current cannot change instantaneously in the coil, you mean. That value of zero is only true at the t=0 instant. Yes, your logic is correct, but you probably need to learn a systematic method of calculation for loop circuits like these in order to solve more complicated problems that are not so intuitive. Ratch