A zener diode, having breakdown voltage equal to 15 V, is

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

Voltage across zener diode is constant.

Current in 1kΩ resistor,

(i)_1kΩ =	15 volt	= 15 mA
	1kΩ

Current in 250Ω resistor,

(i)_1kΩ =	(20 - 15)V	=	5V	A
	250 Ω		250 Ω

=	20	A = 20 mA
	100

∴ (i)_{zener diode} = (20 - 15) = 5 mA