A Zener diode of power rating 1.6 W and breakdown voltage 8 V is used as a regulator for an input fluctuating between 3 V and 10 V. Find the series resistance Rₛ for safe operation. Image
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Question

A Zener diode of power rating 1.6 W and breakdown voltage 8 V is used as a regulator for an input fluctuating between 3 V and 10 V. Find the series resistance Rₛ for safe operation. Image

G1 Physics · Accepted Answer

Maximum safe Zener current = P/(Zener voltage) = 1.6/8 = 0.2 A. At the largest input 10 V, the series resistor must limit current to 0.2 A: R = (10 V − 8 V)/(0.2 A) = 10 Ω. Correct answer: C.