The Zener diode is used for

When a Zener diode is used as a regulator with a Zener voltage of $10 \, V$, nearly five times the load current passes through the Zener diode. What should be the series resistance for the Zener diode if the load resistance is $2 \, k\Omega$ and the unregulated voltage supplied is $16 \, V$?

$A$ 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 voltage across the Zener diode is $6\, V$, then find out the value of the maximum resistance $R$ in this condition. (in $k\Omega$)

In the following circuit,the reading of the ammeter will be (Take Zener breakdown voltage $= 4 \ V$) (in $mA$)

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