Question

In the figure shown, the ideal switch has been open for a long time. If it is closed at t = 0, then the magnitude of the current (in mA) through the $4k\Omega$ resistor at $t=0^{+}$ is .

• A. 1.25

Answer 1

The correct option is A 1.25

At steady state $t=0^{-}$

$\therefore V_C\left(0^{-}\right)=V_C\left(0^{+}\right)=5V$
$I_L\left(0^{-}\right)=I_L\left(0^{+}\right)=1mA$
At, t = 0, switch get closed

Thus, the current through $4\Omega$ resistance is
$I=\frac{5}{4\times {10}^3}=1.25mA$