GATE EC 2016 Set 3 — Question 49

MCQ+2 / -0.67MediumZener RegulatorsDiode CircuitsAnalog CircuitsZener Diode ApplicationsP-N Junction & DiodesElectronic Devices

Analog Circuits → Diode Circuits → Zener Diode Applications

Last updated 5 September 2026

Question

The I-V characteristics of the zener diodes D1 and D2 are shown in Figure I. These diodes are used in the circuit given in Figure II. If the supply voltage is varied from 0 to 100 V, then breakdown occurs in

Correct answer (A) D1 only Solution In Figure II, the two Zener diodes D1 and D2 are connected in series with opposing orientations. 1. When the supply voltage is positive (0 to 100 V), D1 is reverse-biased and D2 is forward-biased. 2. From Figure I, the Zener breakdown voltage for D1 is 80 V and for D2 is 70 V. 3. As the supply voltage increases, D2 remains forward-biased (acting like a closed switch with a small forward drop). 4. D1 is in reverse bias and will enter Zener breakdown when the voltage across it reaches its breakdown threshold of 80 V. 5. Since the supply goes up to 100 V, D1 will definitely break down. D2, being forward-biased, does not undergo breakdown. Therefore, breakdown occurs in D1 only. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (A) D1 only Solution In Figure II, the two Zener diodes D1 and D2 are connected in series with opposing orientations. 1. When the supply voltage is positive (0 to 100 V), D1 is reverse-biased and D2 is forward-biased. 2. From Figure I, the Zener breakdown voltage for D1 is 80 V and for D2 is 70 V. 3. As the supply voltage increases, D2 remains forward-biased (acting like a closed switch with a small forward drop). 4. D1 is in reverse bias and will enter Zener breakdown when the voltage across it reaches its breakdown threshold of 80 V. 5. Since the supply goes up to 100 V, D1 will definitely break down. D2, being forward-biased, does not undergo breakdown. Therefore, breakdown occurs in D1 only.

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