Question

In the given circuit, the breakdown voltage of the Zener diode is 3.0 V. What is the value of I_z ?

• A. 7 mA
• B. 1.5 mA
• C. 5.5 mA
• D. 10 mA

Answer 1

The Correct Option is C

To calculate the current through the Zener diode (\(I_z\)), follow these steps:

Supply Voltage: The circuit's voltage supply is \(V = 10\) V.

Zener Breakdown Voltage: The Zener diode has a breakdown voltage of 3.0 V, meaning the voltage across it is 3.0 V when conducting.

Voltage Across Resistor: The voltage across the 1kΩ resistor is the difference between the supply voltage and the Zener voltage.

\(V_R = V - V_{Z} = 10\, V - 3.0\, V = 7.0\, V\)

Current Through Resistor: Using Ohm’s law, the current through the 1kΩ resistor is:

\(I = \frac{V_R}{R} = \frac{7.0\,V}{1\,k\Omega} = 7\,mA\)

Current Through Zener Diode: The total current \(I\) splits between the Zener diode and the parallel 2kΩ resistor. First, calculate the current through the 2kΩ resistor:

\(I_{\text{2k}} = \frac{V_{Z}}{2\,k\Omega} = \frac{3.0\,V}{2\,k\Omega} = 1.5\,mA\)

Applying Kirchhoff’s current law:

\(I_z = I - I_{\text{2k}} = 7\,mA - 1.5\,mA = 5.5\,mA\)

The Zener diode current (\(I_z\)) is 5.5 mA. The correct answer is 5.5 mA.