Why is there a sudden increase in current in a Zener diode?

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

$A$ Zener diode is used for

The circuit shown below is working as an $8\; V\; dc$ regulated voltage source. When $12 \; V$ is used as input, the power dissipated (in $mW$) in each diode is (considering both zener diodes are identical).

An experiment is performed to determine the $I-V$ characteristics of a Zener diode,which has a protective resistance of $R = 100 \,\Omega$ and a maximum power dissipation rating of $P = 1 \,W$. The minimum voltage range of the $DC$ source in the circuit is

The reading of the ammeter in the following circuit will be in $mA$.