Question

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

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

Answer 1

Answer: (D)

$9 \,mA$

Answer 2

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