JEE Main 2024 · Physics · Semiconductors and Communication · easy

In a Zener-diode voltage regulator, the Zener breakdown voltage is 6 V, the unregulated input is 15 V, the series resistor is 200 Ω and the load…

Single correct option

In a Zener-diode voltage regulator, the Zener breakdown voltage is

6\ \mathrm{V}

, the unregulated input is

15\ \mathrm{V}

, the series resistor is

200\ \Omega

and the load resistor is

1\ \mathrm{k\Omega}

connected across the diode. The current through the Zener diode is

Show answer and solution

Answer: (B) $39\ \mathrm{mA}$

The Zener holds the voltage across the load at

6\ \mathrm{V}

. Current through the series resistor:

I=\dfrac{15-6}{200}=45\ \mathrm{mA}

. Load current:

I_L=\dfrac{6}{1000}=6\ \mathrm{mA}

. By Kirchhoff's current law the diode carries

I_Z=45-6=39\ \mathrm{mA}

. Choosing

45

mA ignores the load;

75

mA would use

15/200

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