GATE EC Diode Circuits questions

In the circuit of the given figure, assume that the diodes are ideal and the meter is an average indicating ammeter. The ammeter will read

A Zener diode in the circuit shown in the figure is has a knee current of $5 \mathrm{~mA}$, and a maximum allowed power dissipation of $300 \mathrm{~mW}$. What are the minimum and maximum load currents that can be drawn safely from the circuit, keeping the output voltage $\mathrm{V}_{\mathrm{o}}$ constant at $6 \mathrm{~V}$?

A zener diode works on the principle of

The $6 \mathrm{~V}$ Zener diode shown in given figure has zero Zener resistance and a knee current of $5 \mathrm{~mA}$. The minimum value of $R$ so that the voltage across it does not fall below $6 \mathrm{~V}$ is

A $\text{P-N}$ junction series with a $100$ ohms resistor, is forward based so that a current of $100 \mathrm{~mA}$ flows. If the voltage across this combination is instantaneously reversed to $10 \mathrm{~V}$ at $t=0$, the reverse current that flows through the diode at $t=0$ is approximately given by