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) 10mA

B) 15mA

C) 20 mA                  

D) 5 mA

Correct Answer: D

Solution :

                For                  \[\frac{0.1}{0.8}={{\left[ \frac{50}{400} \right]}^{n-1}}\]                        \[\log \frac{0.1}{0.8}=\left( n-1 \right)\log \frac{50}{400}\]                   For \[\log \frac{1}{8}=\left( n-1 \right)\log \frac{1}{8}\]           \[0.90=\left( n-1 \right)0.90\]                   \[\Rightarrow \]          \[2Na+2{{H}_{2}}O\to 2NaOH+{{H}_{2}}\uparrow \]                  = 5 mA