When the Zener diode is used as a voltage regulator,it is connected in

$A$ Zener diode, having a breakdown voltage of $15 \text{ V}$, is used in a voltage regulator circuit as shown. The current through the Zener diode is (in $\text{ mA}$)

If the current in the Zener diode is five times the current in $R_1$ and the breakdown voltage of the diode is $6 \text{ V}$,find the value of $R$.

Two Zener diodes ($A$ and $B$) having breakdown voltages of $6\, V$ and $4\, V$ respectively,are connected as shown in the circuit below. The output voltage $V_{0}$ variation with input voltage linearly increasing with time,is given by: $(V_{\text{input}} = 0\, V$ at $t = 0)$ (figures are qualitative).

For the given circuit,the power across the zener diode is ..... $mW$.

Consider the following statements $(A)$ and $(B)$ and identify the correct answer.
$(A)$ $A$ Zener diode is connected in reverse bias when used as a voltage regulator.
$(B)$ The potential barrier of a $p-n$ junction typically lies between $0.1 \, V$ to $0.3 \, V$.