A zener diode of power rating 1.6 W and breakdown voltage 8 V is used as a voltage regulator for an input that can rise to 10 V. The minimum series resistance Rₛ for safe operation is: Image
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Question

A zener diode of power rating 1.6 W and breakdown voltage 8 V is used as a voltage regulator for an input that can rise to 10 V. The minimum series resistance Rₛ for safe operation is: Image

G1 Physics · Accepted Answer

Maximum safe zener current is I(Z,max) = P(max)/V(Z) = 1.6/8 = 0.2 A At the maximum input voltage 10 V, the series resistor must drop 10 − 8 = 2 V Therefore, Rₛ = 2/0.2 = 10 Ω Hence option C follows.