50 TOP SEMICONDUCTOR DIODE Questions and Answers pdf | MCQs

SEMICONDUCTOR DIODE Questions and Answers pdf :-

1. A crystal diode has ………

one pn junction
two pn junctions
three pn junctions
none of the above
ANS: 1

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

kΩ
Ω
MΩ
none of the above
ANS: 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
ANS: 1

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

kA
mA
μA
A
ANS: 3

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

2.5 V
3 V
10 V
0.7 V
ANS: 4

6. A crystal diode is used as ……………

an amplifier
a rectifier
an oscillator
a voltage regulator
ANS: 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
ANS: 3

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

conductor
insulator
resistance material
none of the above
ANS: 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
ANS: 4

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

minority carriers
majority carriers
junction capacitance
none of the above
ANS: 1

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

remains the same
decreases
increases
becomes zero
ANS: 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
ANS: 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
ANS: 3

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

applied voltage
breakdown voltage
forward voltage
barrier potential
ANS: 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
ANS: 1

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

forward
inverse
poor
reverse
ANS: 1

17. A crystal diode is a …………… device

non-linear
bilateral
linear
none of the above
ANS: 1

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

reverse
forward
forward or reverse
none of the above
ANS: 2

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

forward characteristic
doping level
reverse characteristic
PIC rating
ANS: 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
ANS: 3

21. A zener diode has ………..

one pn junction
two pn junctions
three pn junctions
none of the above
ANS: 1

22. A zener diode is used as …………….

an amplifier
a voltage regulator
a rectifier
a multivibrator
ANS: 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
ANS: 3

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

reverse
forward
either reverse or forward
none of the above
ANS: 1

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

forward
reverse
both forward and reverse
none of the above
ANS: 2

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

constant voltage
constant current
constant resistance
none of the above
ANS: 1

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

is forward biased
is reverse biased
carrier more than rated current
none of the above
ANS: 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
ANS: 2

29. A zener diode is …………………. device

a non-linear
a linear
an amplifying
none of the above
ANS: 1

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

undefined
sharp
zero
none of the above
ANS: 2

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

solid state
vacuum tube
gas tube
none of the above
ANS: 1

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

lighting purposes
heaters
using in electronic equipment
none of the above
ANS: 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
ANS: 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
ANS: 2

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

2
1.21
2.5
0.48
ANS: 4

36. There is a need of transformer for ………………..

half-wave rectifier
centre-tap full-wave rectifier
bridge full-wave rectifier
none of the above
ANS: 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
ANS: 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
ANS: 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
ANS: 2

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

paper capacitor
mica capacitor
electrolytic capacitor
air capacitor
ANS: 3

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

paper capacitor
air capacitor
mica capacitor
electrolytic capacitor
ANS: 1

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

choke input
capacitor input
resistance input
none of the above
ANS: 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
ANS: 4

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

40.6 %
81.2 %
50 %
25 %
ANS: 1

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

half-wave rectifier
centre-tap full-wave rectifier
bridge full-wave rectifier
none of the above
ANS: 3

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