Let the magnitude of the gain in the inverting op - amp amplifier circuit shown be $$x$$ with switch $${S_1}$$ open. When the switch $${S_1}$$ is closed, the magnitude of gain becomes.

A non inverting op - amp amplifier is shown in figure. The o/p voltage is

The depletion region (or) space charge region (or) transition region in a semiconductor $$p-n$$ junction diode has

The unit impulse response of a system is given as $$c\left( t \right) = - 4{e^{ - t}} + 6{e^{ - 2t}}.\,\,\,$$ The step response of the same system for $$\,t \ge 0$$ is equal to