Question

A zener diode of power rating 1.6 W is used as a voltage regula tor. If the zener diode has a breakdown voltage of 8 V and it has to regulate voltage fluctuating between 3 V and 10 V, what is the value of resistance Rs for safe operation of the diode?

• A. 10 Ω
• B. 12 Ω
• C. 13 Ω
• D. 13.3 Ω

Hint:

For Zener diode regulator design, always calculate the resistor value based on the maximum input voltage to ensure the Zener diode doesn’t exceed its power rating. Neglecting load current provides a safety margin

Answer 1

The Correct Option is A

Calculation of Series Resistance (\( R_s \)):

Step 1: Calculate Total Current (\( I_t \))

The total current is given by:

\[ I_t = \frac{P_t}{V_t} \]

Substitute the given values:

\[ I_t = \frac{1.6}{8} = 0.2 \, \text{A} \]

Step 2: Use Ohm’s Law to Find Series Resistance (\( R_s \))

The voltage drop across \( R_s \) is:

\[ \Delta V = 10 - 8 = 2 \, \text{V} \]

Using Ohm’s Law:

\[ R_s = \frac{\Delta V}{I_t} \]

Substitute the values:

\[ R_s = \frac{2}{0.2} \]

Step 3: Simplify

\[ R_s = 10 \, \Omega \]

Conclusion:

The series resistance (\( R_s \)) is 10 Ω.