Q.
A zener diode, having breakdown voltage equal to $15\ V$, 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 $mA$
Explanation
(b) Voltage across zener diode is constant
[image:14_image234.emf]
$i_{1k\Omega} = \frac{15\ volt}{1k\Omega} = 15mA$
$i_{250\Omega} = \frac{(20 - 15)V}{250\Omega} = \frac{5V}{250\Omega} = \frac{20}{1000}A = 20mA$
$\therefore i_{zener\ diode} = (20 - 15) = 5\ mA$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.