The circuit shown in the figure determine the current through zener diode. (Given : zener diode break down voltage `Vz=5.6 V`) (A) `7mA` (B) `17mA` (C) `10mA` (D) `15mA`

Options

A. 5 mA
B. 17 mA
C. 10 mA
D. 7 mA

Answer

To determine the current through the Zener diode in the given circuit, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Zener diode breakdown voltage, \( V_z = 5.6 \, V \)
- Resistor values: \( R_1 = 200 \, \Omega \) and \( R_2 = 800 \, \Omega \)
- Supply voltage, \( V_s = 9 \, V \)

2. **Determine the Current through the 800 Ohm Resistor (I2):**
- Since the Zener diode is in parallel with the 800 Ohm resistor, the voltage across the resistor is equal to the Zener voltage.
- Using Ohm's law, the current through the 800 Ohm resistor can be calculated as:
\[ I_2 = \frac{V_z}{R_2} = \frac{5.6 \, V}{800 \, \Omega} = 0.007 \, A = 7 \, mA \]

3. **Apply Kirchhoff's Voltage Law (KVL) to Find I1:**
- We will analyze the loop containing the supply voltage, the 200 Ohm resistor, and the Zener diode.
- According to KVL:
\[ V_s - I_1 \cdot R_1 - V_z = 0 \]
- Rearranging gives:
\[ I_1 = \frac{V_s - V_z}{R_1} = \frac{9 \, V - 5.6 \, V}{200 \, \Omega} = \frac{3.4 \, V}{200 \, \Omega} = 0.017 \, A = 17 \, mA \]

4. **Use Kirchhoff's Current Law (KCL) to Find Zener Current (Iz):**
- At the junction point A, applying KCL:
\[ I_z = I_1 - I_2 \]
- Substitute the values of \( I_1 \) and \( I_2 \):
\[ I_z = 17 \, mA - 7 \, mA = 10 \, mA \]

5. **Conclusion:**
- The current through the Zener diode \( I_z \) is \( 10 \, mA \).

### Final Answer:
The current through the Zener diode is \( 10 \, mA \) (Option C).

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