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