Q 12-14-021NEETJEE MainMedium
A $10$ V Zener diode has a maximum power rating of $0.5$ W. It is connected to a $20$ V supply through a series resistor with no load connected. The minimum value of the series resistor that protects the Zener is
Answer: (A) $200\ \Omega$
Maximum Zener current $= \dfrac{P}{V_Z} = \dfrac{0.5}{10} = 50$ mA.
With no load, all of it flows through the resistor, which has $20 - 10 = 10$ V across it:
$R_{\min} = \dfrac{10}{0.05} = 200\ \Omega$.
Solution by Sreeraj P, M.Sc Physics