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A 0.03 H inductor and a 0.15 kohm resistor are joined in series with a 15 V battery. The switch K1 has been closed a long time. At t = 0, K1 is opened and K2 is closed at the same instant, so the inductor now discharges through the resistor. Find the current at t = 1 ms (use e⁵ = 150).
- 0.67 mA
- 6.7 mA
- 100 mA
- 67 mA
Correct answer: 0.67 mA
Solution
Before switching, the inductor carries the steady current I0 = V/R. After K1 opens and K2 closes, the inductor current decays exponentially with time constant L/R. Evaluate at t = 1 ms using e⁵ = 150.
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