Consider the following statements:
Statement $(A)$: The resistance of an ideal diode in forward biased condition is zero.
Statement $(B)$: In a half-wave rectifier,the load current flows only for every half cycle of the input signals.
Statement $(C)$: In the breakdown region,a Zener diode behaves as a constant voltage source.

$A$ thermoelectric refrigerator works on

Select the correct statements from the following:

Arvind needs to identify the electrical components from a group of components labelled as $A, B, C$ and $D$. He performed some simple tests and obtained the following observations:
$(a)$ $A$ has a silver ring at one end,with two terminals. It conducts electricity only in one direction.
$(b)$ $B$ is connected to a $D.C.$ source,but the current gradually decreases and becomes zero. It is a two-terminal device and behaves the same in both directions.
$(c)$ $C$ is a two-terminal device,which conducts electricity only in one direction,while emitting light.
$(d)$ $D$ is a two-terminal device with several coloured rings on it. It conducts current in both directions with the same steady current.
The correct identification of $A, B, C$ and $D$ are respectively:

The resultant voltage gain in a series combination of two or more amplifiers is .......

If in a $p-n$ junction diode,a square input signal of $5 \ V$ to $-5 \ V$ is applied as shown,which of the following represents the output signal across $R_L$?