A zener diode having zener voltage 8   V and power dissipation rating of 0 . 5   W is connected…

A zener diode having zener voltage $8 V$ and power dissipation rating of $0.5 W$ is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance $R_p$ is _____$\mathrm{\Omega }.$