GATE EC 2018 Set 1 Q26 — Electronic Devices

The circuit shown in the figure is used to provide regulated voltage $(5 V)$ across the $1\: k\Omega$ resistor. Assume that the Zener diode has a constant reverse breakdown voltage for a current range, starting from a minimum required Zener current, $I_{Z min}=2\:mA$ to its maximum allowable current. The input voltage $V_{I}$  may vary by $5\%$ from its nominal value of $6\: V$. The resistance of the diode in the breakdown region is negligible.

The value of $R$ and the minimum required power dissipation rating of the diode, respectively, are