Question

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

Answer 1

Current through `250 Omega`
`l_(1)=("Net voltage")/("Resistance") =((20-15)V)/(250 Omega) =20 xx 10^(-3) A =20 mA`
Current through `1 kOmega` is
`l_(2) =(15V)/(1kOmega) =15xx10^(-3) A =15mA`
So, current through diode is `l_(1)-l_(2) =20 mA-15mA=5mA`