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Homework Statement
A series RL transient circuit is connected to a voltage source of E= 40V through a switch as shown. Suppose the switch is closed at time t=0μs and it was observed that the current iL flowing through the inductor rises to 4mA at time t=20μs and remains at 4mA after t=20μs.
(i) Find the RL time constant τ in μs for the storage phase. Resistor given is 10kΩ
The Attempt at a Solution
iL=E/R(1e^{t/τ})
0.004=40/10000(1e^{20x106}/τ)
0.004=0.004(1e^{20x106}/τ) > 0.0040.004=0
0=e^{20x106}/τ > Wanted to take ln for both side, ln 0 =error
unable to continue, please help, thanks.
(ii) Calculate the amount of energy Wl in nJ, stored in the inductor after 1 minute.
How do we know 1min=60sec>>5time constant?
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