BSNL EXAMS MCQ’s ( Electronics & Communication ) 1. Power diode is generally made from Silicon Germanium Both None of these 2. When the both junction of NPN diode is reverse biased, then the diode is in which mode Active Cutoff Saturation inverted 3. Which transistor mode gives the inverted output Common Emitter Common Base Common Collector None of these 4. Which coupling gives the higher gain in case of amplifier Capacitor coupling Impedance coupling Transformer coupling None of these 5. Which distortion is least objectionable in audio amplification Phase Frequency Harmonic Inter mediation 6. A narrow band amplifier has a band pass nearly…………of central frequency
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BSNL EXAMS MCQ’s ( Electronics & Communication )
1. Power diode is generally made from
Silicon
Germanium
Both
None of these
2. When the both junction of NPN diode is reverse biased, then the diode is in which mode
Active
Cutoff
Saturation
inverted
3. Which transistor mode gives the inverted output
Common Emitter
Common Base
Common Collector
None of these
4. Which coupling gives the higher gain in case of amplifier
Capacitor coupling
Impedance coupling
Transformer coupling
None of these
5. Which distortion is least objectionable in audio amplification
Phase
Frequency
Harmonic
Inter mediation
6. A narrow band amplifier has a band pass nearly…………of central frequency
33.3%
10%
50%
25%
7. Phase shift oscillator consists
RL
RC
RLC
LC
8. Multivibrater Produces
Sine wave
Square wave
Smooth wave
sawtooth
9. Convert the 101101 Binary number into octal no
65
55
51
45
10. The number10 is represented in BCD Number System
10100
1100
010111
None of these
11. Which PNP device has a terminal for synchronizing purpose
SCS
Triac
Diac
SUS
12. Addition of indium in semiconductor crystal makes
PNP
NPN
PNPN
NPNP
13. Free electron exists in which band
1
2
3
Conduction band
14. Ripple factor of half wave rectifier
1.21
0.48
0.5
None of these
15. Transistor that can be used in enhancement mode
NPN
UJT
JFET
MOSFET
16. Following contributes to harmonic distortion in Amplifier
+Ve feedback
–Ve feedback
Defective active device
None of these
17. High cutoff frequency
CB
CC
CE
None of these
18. Which is used as data selector?
Encoder
Decoder
modulator
Demodulator
19. Read write capable memory
RAM
ROM
Both
None of these
20. the radix or base of hexadecimal number system is -----------
8
16
5
none of these
21. the no of 1’s in the binary representation of the expression 162*9+162*7+16*5+3 are
10
23
6
4
22. the no of latches in F/F are -------
1
2
3
4
23. how many flip-flops are required to construct Mod -12 counter
5
4
12
none
24. which logic gate has the output is compliment of its input ----------
OR
AND
NOT
X-OR
25. no.of 2-input multiplexers needed to construct a 210 input multiplexer…….
12
31
20
16
26. Any number with an exponent of zero is equal to:
zero
one
that number
ten
27. In the decimal numbering system, what is the MSD?
The middle digit of a stream of numbers
The digit to the right of the decimal point
The last digit on the right
The digit with the most weight
28. Which of the following statements does NOT describe an advantage of digital technology?
The values may vary over a continuous range.
The circuits are less affected by noise.
The operation can be programmed.
Information storage is easy.
29. The generic array logic (GAL) device is ________.
one-time programmable
reprogrammable
a CMOS device
reprogrammable and a CMOS device
30. The range of voltages between VL(max) and VH(min) are ________.
unknown
unnecessary
unacceptable
between 2 V and 5 V
31. What is a digital-to-analog converter?
It takes the digital information from an audio CD and converts it to a usable form.
It allows the use of cheaper analog techniques, which are always simpler.
It stores digital data on a hard drive.
It converts direct current to alternating current.
32. What are the symbols used to represent digits in the binary number system
0,1
0,1,2
0 through 8
1,2
33. A full subtracter circuit requires ________.
two inputs and two outputs
two inputs and three outputs
three inputs and one output
three inputs and two outputs
34. The output of an AND gate is LOW ________.
all the time
when any input is LOW
when any input is HIGH
when all inputs are HIGH
35. Give the decimal value of binary 10010.
6
9
18
20
36. A mathematical operation for finding the area under the curve of a graph is called
__________.
differentiation
integration
curve averaging
linear regression
37. .An astable multivibrator is also known as a:
one-shot multivibrator
free-running multivibrator
bistable multivibrator
monostable multivibrator
38. A sample-and-hold circuit consists of _________.
An op-amp, an analog switch, and an inductor
An op-amp, an analog switch, and a capacitor
two op-amps, an analog switch, and a variable resistor
two op-amps, an analog switch, and a capacitor
39. An example of potential energy is:
tea-kettle steam
a moving vehicle
the sun
a battery
40. What is the applied voltage for a series RLC circuit when IT = 3 mA, VL = 30 V, VC = 18 V, and
R = 1000 ohms?
3.00 V
12.37 V
34.98 V
48.00 V
41. The number of digits in octal system is?
8
7
8 or 7
10
42. The number of digits in hexadecimal system is?
15
10
16
8
43. The number of bits in a nibble is?
8
2
4
16
44. The digit F in hexadecimal system is equivalent to number...........in decimal system?
16
15
17
8
45. Which of the following binary number is equivalent to decimal 10?
1010
1000
1001
1100
46. The number FF in a hexadecimal system is equivalent to number..........in a decimal system ?
256
240
255
239
47. ICs are?
analog
digital
both Analog and digital
mostly analog
48. The rate of change of digital signals between High and low level is?
very fast
fast
slow
very slo
49. Digital circuits mostly use?
Diodes
Bipolar transistors
Diodes and bipolar transistor
Bipolar transistors and FETs
50. Two voltages are-5V and-10V.In positive logic?
-5V is 1 and -10V is 0
-10 Vis 1 and-5V is 0
-5V is 1 and -10V is1
-5V is 0 and -10V is 0
51. Logic Pulser ?
generate short duration pulses
generate long duration pules
generate ideal pulses
None of these
52. The number of LED displays in duration in logic probe are?
1
2
4
1 or 2
53. The output impenitence of a logic pulser is?
Low
High
May be low or high
Can't say
54. A current transducer respond to?
steady current only
pulsating current only
both pulasting and steady
none of these
55. .Logic analyser is?
a multi channel oscilloscope
similar to logic pulser
similar to current tracer
none of above
56. Which of these are two state device?
Lamp
magnetic tap
punched card
All the above
57. In the decimal number 27,the digit 2 represent ?
2
0.2
20
200
58. In Hexadecimal number system,A is equal to decimal number?
10
17
11
18
59. Hexadecimal number F is equal to octal number?
15
17
16
18
60. Hexadecimal number E is equal to binary?
1110
1001
1111
1101
61. Binary number 1101 is equal to octal number?
17
15
16
14
62. octal number 12 is equal to decimal number?
8
9
11
10
63. 100101 is equal to decimal number ?
27
37
17
47
64. Decimal number 10 is equal to binary number?
1110
1001
1010
1000
65. Decimal number 110011011001 is equal to decimal number?
3289
1289
2289
289
66. Which of the following is the ideal characteristics of OP-AMP
Bandwidth is zero
Offset voltage is infinite
Output voltage is infinite
CMMR is infinite
67. A signal has frequency components from 300Hz to 2 kHZ.The minimum possible rate at
which the signal has to be sampled
600Hz
900Hz
2kHz
4Khz
68. Negative feed back in amplifiers is used to
Improves the SNR at the input
Improves the SNR at the output
Reduces distortion
Doesn’t effect the SNR at the output
69. In PCM system, if the quantization levels are increased from 2 to 8, the relative bandwidth
requirement will.
remain same
be doubled
be tripled
become four times
70. Fulladder consists of
1 half adder and 1 AND gate
2 Half adders and 1 XOR gate
1 Half adder and 1 OR gate
2 Half adders and 1 OR gate
71. Flipflop is a
Monostable
Bistable
Astable
None of these
72. For a 8 bit counter the number of filp flops required is
2
4
3
1
73. In 8085 microprocessor The data bus has
Unidirectional
Bi-directional
Both
None of these
74. The number of hardware interrupts in 8085 Microprocessors
2
4
3
5
75. Which of the following is used for Wider bandwidth in amplifiers
Cascade connection
Darlington
Cascode connection
Both A and B
76. When modulation changed from 0 to 1 then power increases by
20%
40%
50%
90%
77. The highest modulation frequency typically used in AM broadcast is
5KHz
10kHz
15kHz
22kHz
78. Time division multiplexing used in
Analog communication
Digital communication
Both A and B
None of these
79. Gray code is also called as
Cyclic code
Reflected code
Both A and B
None of these
80. Common base amplifier has
High input impedance
High output impedance
Low output impedance
None
81. In negative feedback the distortion will
Increase
Decrease
Some times increase some times decrease
None of the above
82. Barkausens criteria is
Aß=1
Aß=-1
Both A and B
None
83. Which of the following is more stable
Wien bridge oscillator
Crystal oscillator
RC oscillatory
Colpitts Oscillator
84. The forbidden energy gap for germanium atom
1.1 ev
0.7 ev
0.3 ev
None
85. For reflection coefficient ?=0.5,VSWR is
2
3
4
8
86. The unit of µ0e0 is
Farad henry
Meter2/sec2
Amp-sec
None
87. A low loss transmission line has
R=wl, G=wC
R<<wL, G<<wC
R>>wL, G>>wC
None
88. Which of the following has longest wavelength
HF
VHF
UHF
SHF
89. For a good conductor, the skin depth varies:
Directly as frequency f
Directly as √f
Inversely as √f
None
90. .An antenna that is circularly polarized is
Helical
Yagi-uda
Parabolic
Small circular loop
91. In series resonance circuit the voltage source is
Low resistance
High resistance
Zero resistance
None of the above
92. A network is non linear if it doesn’t satisfy
Homogeneity
Superposition theorem
Associative condition
Both A and B
93. The gray code for number 6 is
1100
1001
0101
0110
94. What is the addressing mode used in instruction LDA 0345
Direct
Indirect
Immediate
Indexed
95. How many modes of operations are there in 8255 PPI?
1
2
3
4
96. Which of the following has lowest efficiency
Class A
Class B
Class AB
Class C
97. The differential amplifier has a differential gain of 20000 CMRR=80dB. The common mode
gain is
2
1
0.5
0
98. Super-beta transistor is a
Cascade configuration
Cascode configuration
Darlington configuration
Matched pair
99. To eliminate ghosts in the picture
Use a longer transmission line
Connect a booster
Change the antenna orientation or location
Twist the transmission line
100. Vividh bharati programme is transmitted in
Short waves
Medium frequency
Very high frequency
None
101. The double energy transients occur in the
R-L circuit
R-C circuit
Pure inductive circuit
R-L-C circuit
102. The unit of flux is
Weber
Tesla
Joule
Weber/m2
103. The transfer function H(s)=(s2-5s+100)/s2+5s+100 represents
A high pass filter
A band elimination filter
A resonator
An all pass filter
104. Double spotting in superhetrodyne receiver is caused by
Poor front-end rejection
Misalignment of receiver
Detuning of one or more IF stages
Non-functioning of AGC
105. The ratio of distance between cochannel to radius of the cell (D/R)is
N
√N
3√N
√(3N)
106. MAHO stands for
Mobile additive hand off
Mobile assisted Hand off
Mounted additive hand off
None of the above
107. Traffic intensity is measured by
Traffic
Erlangs
Seconds
Decibels
108. Frequency selective fading means
Band width of the signal is greater than the band width of the channel
Delay speed is greater than symbol speed
Both A and B
None of these
109. HLR stands for
Home localized rectifier
Home location register
Home loyality register
None
110. A receiver has poor if selectivity,it will therefore also have poor
Blocking
Double spotting
Diversity reception
Sensitivity
111. The number of lines per second in the US monochrome TV system