If a Zener diode `(V_(Z)=5 and I_(Z)=10 mA)` is connected in series with a resistance and 20 V is applied across the combination, then the maximum resistance one can use without spoiling zener action is

Options

A. `20kOmega`
B. `15kOmega`
C. `10kOmega`
D. `1.5kOmega`

Explanation

To solve the problem, we need to determine the maximum resistance that can be used in series with a Zener diode without spoiling its action when a 20 V supply is applied. The Zener diode has a Zener voltage \( V_Z = 5 \, V \) and a Zener current \( I_Z = 10 \, mA \).

### Step-by-Step Solution:

1. **Identify the total voltage applied**:
The total voltage applied across the series combination is \( V_{total} = 20 \, V \).

2. **Determine the voltage across the resistor**:
The Zener diode maintains a constant voltage of \( V_Z = 5 \, V \) across it when in reverse bias. Therefore, the voltage drop across the resistor \( V_R \) can be calculated as:
\[ V_R = V_{total} - V_Z = 20 \, V - 5 \, V = 15 \, V \]

3. **Determine the Zener current**:
The Zener current \( I_Z \) is given as \( 10 \, mA = 0.01 \, A \).

4. **Use Ohm's Law to find the maximum resistance**:
According to Ohm's Law, the resistance \( R \) can be calculated using the formula:
\[ R = \frac{V_R}{I_Z} \]
Substituting the values:
\[ R = \frac{15 \, V}{0.01 \, A} = 1500 \, \Omega \]

5. **Convert resistance to kilo-ohms**:
To express the resistance in kilo-ohms:
\[ R = 1500 \, \Omega = 1.5 \, k\Omega \]

6. **Conclusion**:
The maximum resistance that can be used without spoiling Zener action is \( 1.5 \, k\Omega \).

### Final Answer:
The maximum resistance one can use without spoiling Zener action is \( 1.5 \, k\Omega \).

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