A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles.

In the circuit shown below, Q₁ has negligible collector-to-emitter saturation voltage and the diode drops negligible voltage across it under forward bias. If V_CC is +5 V, X and Y are digital signals with 0 V as logic 0 and V_CC as logic 1, then the Boolean expression for Z is

The divergence of the vector field $$\overrightarrow A\;=\;x{\widehat a}_x\;+\;y{\widehat a}_y\;+\;z{\widehat a}_z$$ is

The return loss of a device is found to be 20 dB. The voltage standing wave ratio (VSWR) and magnitude of reflection coefficient are respectively.