## Multiple Choice Questions and Answers on Semiconductor Diode

**Q1. A crystal diode has ………**

- one pn junction
- two pn junctions
- three pn junctions
- none of the above

**Answer : 1**

**Q2. A crystal diode has forward resistance of the order of ……………**

- kΩ
- Ω
- MΩ
- none of the above

**Answer : 2**

**Q3. If the arrow of crystal diode symbol is positive w.r.t. bar, then diode is ………….. biased.**

- forward
- reverse
- either forward or reverse
- none of the above

**Answer : 1**

**Q4. The reverse current in a diode is of the order of ……………….**

- kA
- mA
- μA
- A

**Answer : 3**

**Q5. The forward voltage drop across a silicon diode is about …………………**

- 2.5 V
- 3 V
- 10 V
- 0.7 V

**Answer : 4**

**Q6. A crystal diode is used as ……………**

- an amplifier
- a rectifier
- an oscillator
- a voltage regulator

**Answer : 2**

**Q7. The d.c. resistance of a crystal diode is ………….. its a.c. resistance**

- the same as
- more than
- less than
- none of the above

**Answer : 3**

**Q8. An ideal crystal diode is one which behaves as a perfect ……….. when forward biased.**

- conductor
- insulator
- resistance material
- none of the above

**Answer : 1**

**Q9. The ratio of reverse resistance and forward resistance of a germanium crystal diode is about ………….**

- 1 : 1
- 100 : 1
- 1000 : 1
- 40,000 : 1

**Answer : 4**

**Q 10. The leakage current in a crystal diode is due to …………….**

- minority carriers
- majority carriers
- junction capacitance
- none of the above

**Answer :1**

**Q11. If the temperature of a crystal diode increases, then leakage current ………..**

- remains the same
- decreases
- increases
- becomes zero

**Answer :3**

**Q12. The PIV rating of a crystal diode is ………….. that of equivalent vacuum diode**

- the same as
- lower than
- more than
- none of the above

**Answer :2**

**Q13. If the doping level of a crystal diode is increased, the breakdown voltage………….**

- remains the same
- is increased
- is decreased
- none of the above

**Answer :3**

**Q14. The knee voltage of a crystal diode is approximately equal to ………….**

- applied voltage
- breakdown voltage
- forward voltage
- barrier potential

**Answer :4**

**Q15. When the graph between current through and voltage across a device is a straight line, the device is referred to as ……………….**

- linear
- active
- nonlinear
- passive

**Answer :1**

**Q16. When the crystal current diode current is large, the bias is …………**

- forward
- inverse
- poor
- reverse

**Answer :1**

**Q17. A crystal diode is a …………… device**

- non-linear
- bilateral
- linear
- none of the above

**Answer :1**

**Q18. A crystal diode utilises …………….. characteristic for rectification**

- reverse
- forward
- forward or reverse
- none of the above

**Answer :2**

**Q19. When a crystal diode is used as a rectifier, the most important consideration is ………..**

- forward characteristic
- doping level
- reverse characteristic
- PIC rating

**Answer :4**

**Q20. If the doping level in a crystal diode is increased, the width of depletion layer………..**

- remains the same
- is decreased
- in increased
- none of the above

**Answer :3**

**Q21. A zener diode has ………..**

- one pn junction
- two pn junctions
- three pn junctions
- none of the above

**Answer :1**

**Q22. A zener diode is used as …………….**

- an amplifier
- a voltage regulator
- a rectifier
- a multivibrator

**Answer :2**

**Q23. The doping level in a zener diode is …………… that of a crystal diode**

- the same as
- less than
- more than
- none of the above

**Answer :3**

**Q24. A zener diode is always ………… connected.**

- reverse
- forward
- either reverse or forward
- none of the above

**Answer :1**

**Q25. A zener diode utilizes ……….. characteristics for its operation.**

- forward
- reverse
- both forward and reverse
- none of the above

**Answer :2**

**Q26. In the breakdown region, a zener didoe behaves like a …………… source.**

- constant voltage
- constant current
- constant resistance
- none of the above

**Answer :1**

**27. A zener diode is destroyed if it…………..**

- is forward biased
- is reverse biased
- carrier more than rated current
- none of the above

**Answer :3**

**Q28. A series resistance is connected in the zener circuit to………..**

- properly reverse bias the zener
- protect the zener
- properly forward bias the zener
- none of the above

**Answer :2**

**A29. A zener diode is …………………. device**

- a non-linear
- a linear
- an amplifying
- none of the above

**Answer :1**

**Q30. A zener diode has ………….. breakdown voltage**

- undefined
- sharp
- zero
- none of the above

**Answer :2**

**Q31. ……………. rectifier has the lowest forward resistance**

- solid state
- vacuum tube
- gas tube
- none of the above

**Answer :1**

**Q32. Mains a.c. power is converrted into d.c. power for ……………..**

- lighting purposes
- heaters
- using in electronic equipment
- none of the above

**Answer :3**

**Q33. The disadvantage of a half-wave rectifier is that the……………….**

- components are expensive
- diodes must have a higher power rating
- output is difficult to filter
- none of the above

**Answer :3**

**Q34. If the a.c. input to a half-wave rectifier is an r.m.s value of 400/√2 volts, then diode PIV rating is ………………….**

- 400/√2 V
- 400 V
- 400 x √2 V
- none of the above

**Answer :2**

**Q35. The ripple factor of a half-wave rectifier is …………………**

- 2
- 1.21
- 2.5
- 0.48

**Answer :4**

**Q36. There is a need of transformer for ………………..**

- half-wave rectifier
- centre-tap full-wave rectifier
- bridge full-wave rectifier
- none of the above

**Answer :2**

**Q37. The PIV rating of each diode in a bridge rectifier is ……………… that of the equivalent centre-tap rectifier**

- one-half
- the same as
- twice
- four times

**Answer :1**

**Q38. For the same secondary voltage, the output voltage from a centre-tap rectifier is ………… than that of bridge rectifier**

- twice
- thrice
- four time
- one-half

**Answer :4**

**Q39. If the PIV rating of a diode is exceeded, ………………**

- the diode conducts poorly
- the diode is destroyed
- the diode behaves like a zener diode
- none of the above

**Answer :2**

**Q40. A 10 V power supply would use …………………. as filter capacitor.**

- paper capacitor
- mica capacitor
- electrolytic capacitor
- air capacitor

**Answer :3**

**Q41. A 1,000 V power supply would use ……….. as a filter capacitor**

- paper capacitor
- air capacitor
- mica capacitor
- electrolytic capacitor

**Answer :1**

**Q42. The ……………….. filter circuit results in the best voltage regulation**

- choke input
- capacitor input
- resistance input
- none of the above

**Answer :1**

**Q43. A half-wave rectifier has an input voltage of 240 V r.m.s. If the step-down transformer has a turns ratio of 8:1, what is the peak load voltage? Ignore diode drop.**

- 27.5 V
- 86.5 V
- 30 V
- 42.5 V

**Answer :4**

**Q44. The maximum efficiency of a half-wave rectifier is ………………..**

- 40.6 %
- 81.2 %
- 50 %
- 25 %

**Answer :1**

**Q45. The most widely used rectifier is ……………….**

- half-wave rectifier
- centre-tap full-wave rectifier
- bridge full-wave rectifier
- none of the above

**Answer :3**