In the Fig. given below, the initial capacitor voltage is zero. The switch is closed at $$t = 0.$$ the final steady-state voltage across the capacitor is

A unit step voltage is applied at $$t = 0$$ to a series $$RL$$ circuit with zero initial conditions.

In the series $$RC$$ circuit shown in Fig. the voltage across $$C$$ starts increasing when the $$d.c.$$ source is switched on. The rate of increase of voltage across $$C$$ at the instant just after the switch is closed (i.e., at $$t = {0^ + }$$), will be

The time constant of the network shown in Fig. is