A zener diode, having breakdown voltage 15 V is used in a voltage regulator circuit as shown. The current…

A zener diode, having breakdown voltage 15 V is used in a voltage regulator circuit as shown. The current through the zener diode is
  1. 20 mA
  2. 5 mA
  3. 10 mA
  4. 15 mA

Solution

The voltage drop across $1 \mathrm{k} \Omega$ is 15 V $\therefore \quad$ The current through it is $I=\frac{15 \mathrm{~V}}{1 \times 10^3 \Omega}$ $=15 \times 10^{-3} \mathrm{~A}$
The voltage drop across $250 \Omega=20-15=5 \mathrm{~V}$ $\therefore \quad$ the current through it $I=\frac{V}{R}=\frac{5}{250}=20 \times 10^{-3} \mathrm{~A}$
The current through zener diode is, $I_z=\left(20 \times 10^{-3}\right)-\left(15 \times 10^{-3}\right)=5 \mathrm{~mA}$ *

Asked in: MHT CET 2024 (04 May Shift 1)

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