question_answer

Consider the circuit, the current through the Zener diode is

A) \[20\,\,mA\]                     

B) \[10\,\,mA\]

C) \[15\,\,mA\]                     

D)  \[40\,\,mA\]

Correct Answer: B

Solution :

Consider the circuit shown below. Voltage across \[{{R}_{2}}\] is                 \[{{V}_{{{R}_{2}}}}={{V}_{Z}}=20V\] Current through \[{{R}_{2}}\] is                 \[{{I}_{{{R}_{2}}}}=\frac{{{V}_{{{R}_{2}}}}}{{{R}_{2}}}=\frac{20}{2000}=\frac{1}{100}A=10\,\,mA\] Voltage drop across\[R,\,\,{{V}_{{{R}_{1}}}}=40-20=20V\]                 \[I=\frac{{{V}_{{{R}_{1}}}}}{1000\Omega }=\frac{20}{1000}=\frac{2}{100}=20\,\,mA\] Thus, current through Zener diode                 \[{{I}_{Z}}=I-{{I}_{{{R}_{2}}}}=20\,\,mA-10\,\,mA=10\,\,mA\]