Question

For the circuit shown below, the current through the Zener diode is :

• A. $5mA$
• B. Zero
• C. $14mA$
• D. $9mA$

Answer 1

Answer: (D)

Assuming zener diode doesnot undergo breakdown, current in circuit = $\frac{120}{15000}=8mA$
$\therefore$ Voltage drop across diode = $80V>50V$.
The diode undergo breakdown.
Current is $R_1=\frac{70}{5000}=14mA$
Current is $R_2=\frac{50}{10000}=5mA$
$\therefore$ Current through diode = $9mA$