In the voltage regulator shown below the power dissipation

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In the voltage regulator shown below the power dissipation in the zener diode is—

1. 1 mV
2. 1.5 mV
3. 2 mV
4. 0.5 mV

Correct Option: D

Since in the given problem R_Z is zero. so, in order to calculate the power dissipation across the zener diode. We must calculate the current flowing in zener diode
Where, V_th = Thevenin equivalent voltage
R_th = Thevenin equivalent resistance

V_th =		75	= 50 .	1
		75 + 150		3

=	50	V > V_Z
	3

R_th = 150 \|\| 75 =	150 × 75
	150 + 75

= 50 kΩ

i_Z =		V_th	=	50/3
		R_th + R_L		50 kΩ

= 0.33 mA
Now P_Z = V_Z. i_Z = 15 × 0.33 mA
= 0.5 mW
Hence alternative (D) is the correct choice.