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