Question

A zener diode, having breakdown voltage equal to 15V, is used in a voltage regulator circuit shown in figure.

The current through the diode is

• A. 20 mA
• B. 5 mA
• C. 10 mA
• D. 15 mA

Answer 1

The correct option is B

5 mA

Voltage drop across 250$\Omega$ = 5V

$\therefore$ Current through $250\Omega =\frac{5}{250}=\frac{1}{50}A=20mA$

Current through the $1k\Omega$ resistance

$=\frac{15V}{1000\Omega }=15\times {10}^{-3}A=15mA$

$\therefore$ Current through the diode
$=(20–15)=5mA$.