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

Answer 1

The correct option is A $5mA$

Break down Voltage$=15V$

To find, current through the diode$?$

For $1k\Omega ,$

$i_1=\frac{V}{R}=\frac{15V}{1K\Omega }=\frac{15}{1\times {10}^3}=15mA$

For $250\Omega$

$i=\frac{V}{R}=\frac{20-15}{250}=\frac{5}{250}=\frac{1}{50}A$

$(\frac{1}{50}\times 1000)mA=20mA$

$\therefore i_2=$current through the diode$=i-i_1$

$=(20-15)mA$

$=5mA$