20 Important Diode PYQs for JE Electronics with Answers | SSC JE, ISRO, DRDO, ECIL

20 Important Diode PYQs for JE Electronics DRDO, ISRO, RRB, SSC

These are the most important Diode Previous Year Questions (PYQs) asked in various JE Electronics exams such as SSC JE, ISRO, DRDO, ECIL, and State Polytechnic Lecturer exams. Both conceptual and numerical type questions are included below with answers.

1. In a silicon diode, the barrier potential at room temperature is approximately:
A) 0.1 V B) 0.3 V C) 0.7 V D) 1 V

✅ Answer: C) 0.7 V

2. When a PN junction is forward biased, the width of the depletion layer:
A) Increases B) Decreases C) Remains constant D) None

✅ Answer: B) Decreases

3. In a reverse biased diode, the current mainly consists of:
A) Holes B) Electrons C) Minority carriers D) Majority carriers

✅ Answer: C) Minority carriers

4. If the reverse bias of a diode is increased, the junction capacitance:
A) Increases B) Decreases C) Remains same D) Becomes zero

✅ Answer: B) Decreases

5. A Zener diode is used for:
A) Rectification B) Voltage regulation C) Amplification D) Oscillation

✅ Answer: B) Voltage regulation

6. For a half-wave rectifier using a silicon diode and 230 V AC input, the PIV (Peak Inverse Voltage) is approximately:
A) 230 V B) 325 V C) 460 V D) 650 V

✅ Answer: B) 325 V

7. In a full-wave center-tap rectifier, the PIV of each diode is:
A) Vm B) 2Vm C) Vm/2 D) Vm/√2

✅ Answer: B) 2Vm

8. A diode conducts when:
A) Reverse biased B) Forward biased C) Both D) None

✅ Answer: B) Forward biased

9. If the input voltage to a diode is 10 V DC and forward resistance is negligible, the voltage across the diode is:
A) 10 V B) 0 V C) 9.3 V D) 0.7 V

✅ Answer: D) 0.7 V

10. In a Zener diode, the breakdown voltage mainly depends on:
A) Temperature B) Doping concentration C) Forward current D) Diode area

✅ Answer: B) Doping concentration

11. The ripple frequency in a full-wave rectifier is:
A) Equal to supply frequency B) Twice supply frequency C) Half D) Zero

✅ Answer: B) Twice supply frequency

12. If a diode has reverse saturation current of 10 μA and forward voltage is 0.7 V at 300 K, what happens when temperature increases?

✅ Answer: Reverse saturation current increases (approximately doubles for every 10°C rise)

13. The reverse recovery time of a diode is the time taken for:
A) Forward current to reach zero B) Stored charge to be removed C) Reverse current to reach max D) Forward voltage to fall to zero

✅ Answer: B) Stored charge to be removed

14. Tunnel diode works on the principle of:
A) Avalanche breakdown B) Tunneling C) Thermal runaway D) Diffusion
✅ Answer: B) Tunneling

15. The dynamic resistance of a diode in forward bias region is approximately:
A) High B) Low C) Infinite D) Zero

✅ Answer: B) Low

16. Which diode is used for high-frequency applications?
A) Zener B) Varactor C) Schottky D) Tunnel

✅ Answer: C) Schottky

17. A 10 V Zener diode with Rs = 220 Ω is connected to a 20 V supply. Find Zener current if load current = 20 mA.
Current through Rs = (20 − 10)/220 = 45.45 mA
IZ = 45.45 − 20 = 25.45 mA

✅ Answer: IZ ≈ 25 mA

18. In a half-wave rectifier, the efficiency is:
A) 81.2% B) 40.6% C) 100% D) 50%

✅ Answer: B) 40.6%

19. For a silicon diode, reverse saturation current doubles for every:
A) 5°C rise B) 10°C rise C) 25°C rise D) 50°C rise

✅ Answer: B) 10°C rise

20. Which diode has a negative resistance region?
A) Zener B) Tunnel C) Schottky D) Varactor
✅ Answer: B) Tunnel

Read also : BJT PYQ FOR JE ELECTRONICS 

Conclusion

These 20 Diode PYQs for JE Electronics are crucial for SSC JE, ISRO, DRDO, ECIL, and State JE exams. Understanding diode behavior, characteristics, and applications will help you score better in electronics objective papers.