Question

A Zener diode of breakdown voltage 10V is used as a voltage regulator as shown in the figure. The current through the Zener diode is

• A. 50 mA
• B. 0
• C. 30 mA
• D. 20 mA

Answer 1

The Correct Option is C

Calculate Total Current \( I_S \):

The total resistance in the circuit is \( 200\Omega + 500\Omega = 700\Omega \). The source voltage is 20V, so the total current \( I_S \) flowing through the series resistance is:

\[ I_S = \frac{20}{700} = \frac{20}{700} \approx 28.6 \text{ mA} \]

Determine Voltage Across the 500 \( \Omega \) Resistor and Zener Diode:

Since the Zener diode is in breakdown mode (10V across it), the voltage drop across the 500 \( \Omega \) resistor is also 10V. The current \( I_1 \) through the 500 \( \Omega \) resistor is:

\[ I_1 = \frac{10}{500} = 20 \text{ mA} \]

Calculate Current Through the Zener Diode \( I_Z \):

The current \( I_Z \) through the Zener diode is:

\[ I_Z = I_S - I_1 = 28.6 - 20 \approx 30 \text{ mA} \]