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 _______.

In the following figure, C₁ and C₂ are ideal capacitors. C₁ has been charged to 12 V before the ideal switch S is closed at t = 0. The current i(t) for all t is.

If the unit step response of a network is $$(1-e^{-\alpha t})$$, then its unit impulse response is

In the following circuit, the switch S is closed at t=0. The rate of change of current $$\frac{di}{dt}(0^+)$$ is given by