Question
An inductor (L = 0.03 H) and a resistor (R = 0.15 kΩ) are connected in series to a battery of 15V EMF in a circuit shown. The key K1 has been kept closed for a long time. Then at t = 0, K1 is opened and key K2 is closed simultaneously. At t = 1 ms, the current in the circuit will be:
(
)
-
100 mA
-
67 mA
-
6.7 mA
-
0.67 mA
Solution
D.
0.67 mA
After long time inductor behaves as short-circuit.
At t = 0, the inductor behaves as short circuit.The current,
As K2 is closed, current through the indicator starts decay which is given at any time t as
