A zener diode of power rating 1.6 W is to be used as voltage regulator. If the zener diode has a breakdown of 8 V and it has to regulate voltage fluctuating between 3 V and 10 V. The value of resistance $$R_s$$ for safe operation of diode will be

Given: Power rating = 1.6 W, breakdown voltage $$V_z = 8$$ V, input voltage fluctuates between 3 V and 10 V.

Maximum zener current: $$I_{z,max} = \frac{P}{V_z} = \frac{1.6}{8} = 0.2$$ A

For safe operation, the maximum current through the zener should not exceed 0.2 A. This occurs when the input voltage is maximum (10 V).

The series resistance $$R_s$$ must limit the current:

$$R_s = \frac{V_{input,max} - V_z}{I_{z,max}} = \frac{10 - 8}{0.2} = \frac{2}{0.2} = 10 \text{ } \Omega$$

The correct answer is Option 1: 10 $$\Omega$$.