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                                                        [AIPMT (M) 2011]

A)  10 mA             

B)  15 mA

C)       20 mA             

D)       5 mA

Correct Answer: D

Solution :

For        \[\text{I}\,\text{I}\,\,\text{k}\,\Omega \]

\[{{i}_{1}}=\frac{15}{1}=15\,\text{mA}\]

For        \[\text{I}\,\text{I}\,250\,\Omega \]

\[_{i\,\text{250}\,\text{ }\!\!\Omega\!\!\text{ }}\text{=}\frac{20-15}{250}=\frac{5}{250}\]

\[=\frac{20}{1000}=20\,mA\]

\[\therefore \]      \[{{i}_{\text{zener}}}=20-15=5\,mA\]