**SEMICONDUCTOR DIODE Questions and Answers pdf :-**

**1. A crystal diode has ………**

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

**Answer: 1**

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

- kΩ
- Ω
- MΩ
- none of the above

**Answer: 2**

**3. 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**

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

- kA
- mA
- μA
- A

**Answer: 3**

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

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

**Answer: 4**

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

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

**Answer: 2**

**7. 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**

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

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

**Answer: 1**

**9. 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**

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

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

**Answer: 1**

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

- remains the same
- decreases
- increases
- becomes zero

**Answer: 3**

**12. 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**

**13. 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**

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

applied voltage

breakdown voltage

forward voltage

barrier potential

**Answer: 4**

**15. 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**

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

forward

inverse

poor

reverse

**Answer: 1**

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

non-linear

bilateral

linear

none of the above

**Answer: 1**

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

reverse

forward

forward or reverse

none of the above

**Answer: 2**

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

forward characteristic

doping level

reverse characteristic

PIC rating

**Answer: 4**

**20. 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: 2**

**21. A zener diode has ………..**

one pn junction

two pn junctions

three pn junctions

none of the above

**Answer: 1**

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

an amplifier

a voltage regulator

a rectifier

a multivibrator

**Answer: 2**

**23. 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**

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

reverse

forward

either reverse or forward

none of the above

**Answer: 1**

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

forward

reverse

both forward and reverse

none of the above

**Answer: 2**

**26. 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**

**28. 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**

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

a non-linear

a linear

an amplifying

none of the above

**Answer: 1**

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

undefined

sharp

zero

none of the above

**Answer: 2**

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

solid state

vacuum tube

gas tube

none of the above

**Answer: 1**

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

lighting purposes

heaters

using in electronic equipment

none of the above

**Answer: 3**

**33. 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**

**34. 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**

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

2

1.21

2.5

0.48

**Answer: 2**

**36. 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**

**37. 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**

**38. 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**

**39. 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**

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

paper capacitor

mica capacitor

electrolytic capacitor

air capacitor

**Answer: 3**

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

paper capacitor

air capacitor

mica capacitor

electrolytic capacitor

**Answer: 1**

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

choke input

capacitor input

resistance input

none of the above

**Answer: 1**

**43. 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**

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

40.6 %

81.2 %

50 %

25 %

**Answer: 1**

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

half-wave rectifier

centre-tap full-wave rectifier

bridge full-wave rectifier

none of the above

**Answer: 3**

Q20

the ans should be 2

deplition width inversely depend upon square root of doping.

Sir

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