question_answer

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)  10 mA        

B)  15 mA

C)  20 mA        

D)  5 mA

Correct Answer: D

Solution :

For I \[R=1\,k\Omega \] \[{{i}_{1}}=\frac{15}{1}=15\,mA\] For II \[R=250\Omega \] \[{{i}_{250\Omega }}=\frac{20-15}{250}=\frac{5}{250}\] \[=\frac{20}{1000}=20\,mA\] \[\therefore \] \[{{i}_{zener}}=20-15=5mA\]