Q 12-14-059JEE MainJEE Main 2024 (1 Feb, Shift 1)Medium
In the given circuit, the power rating of the Zener diode is $10\ \text{mW}$. The value of the series resistance $R_s$ needed to regulate the unregulated input supply is
Answer: (A) $\dfrac{3}{7}\ \text{k}\Omega$
Maximum Zener current: $I_Z = \dfrac{P}{V_Z} = \dfrac{10\ \text{mW}}{5\ \text{V}} = 2\ \text{mA}$.
Load current: $I_L = \dfrac{5}{1000} = 5\ \text{mA}$.
Current through $R_s$: $I = 2 + 5 = 7\ \text{mA}$.
$$R_s = \frac{8 - 5}{7\ \text{mA}} = \frac{3}{7}\ \text{k}\Omega$$
Solution by Sreeraj P, M.Sc Physics