Preparation Tips for BEL Probationary Engineer Recruitment Exam

BEL stands as Bharat Electronics Limited and is one of the top electronics company. It recruits students from the branch of Mechanical, Electrical, Civil, Electronics and Computer Science through written test that is known as BEL Probationary Engineers Exam.

BEL is conducting written test for the recruitment of Probationary Engineer on 21st June 2015.The exam will be held in different Centres. Huge numbers of applicants have been applied for BEL Probationary Engineers Requirement. Among all these competition how do you prepare for your exam?

Syllabus for BEL Probationary Engineering Exam

General Syllabus

  1. General English
  2. General Awareness
  3. Quantitative Aptitude
  4. Reasoning Ability

Technical Aptitude

  1. Paper consists questions from the qualifying degree.
General aptitude consists of objective type questions from fundamental engineering subjects and in the specific specializations.

Some Preparation Tips

  1. Practice previous year question papers.
  2. Conduct mock test through online websites.
  3. You need to study on main topics such as Digital Logic Design, Advanced microprocessor and interfacing, Networking, Control Systems, Analog electronics and Digital Electronics, Aptitude and Reasoning, Electrical Machine.
  4. Correct the time accurately.
  5. Try to cover entire syllabus.
  6. After your exam preparation review everything once before attending the exam.
  7. Make short hand notes to make revision during your preparation.
  8. Don’t read any new topics at the last moment of exam.

Books for preparation are

  1. Electrical Machines - Mikesh K. Pathak and Mulukutla S. Sharma
  2. For network analysis and Synthesis – Franklin S. KUO
  3. Automatic Control Systems – Benjamin C. Kuo
  4. Verbal Reasoning – R.S Agarwal
  5. Digital Logic and Computer Design – M.Morris Mano
  6. Microprocessor Architecture, Programming and Application – Ramesh S. Gaonkar
  7. Analytical Reasoning – Shri M.K. Pandey
  8. The Aptitude Test Workbook – Jim Barrett

BEL Exam for the position of Probationary Engineer

For any entrance exam every students must know the exam syllabus, exam pattern, online application dates and date of exam.BEL Probationary Engineer Syllabus 2015 for Mechanical, Computer Science and Electronics Engineers is available on official website Applicants who have applied for Probationary Engineer have 394 vacancies. Students can check BEL Probationary Engineer Exam pattern.

BEL Exam syllabus for probationary engineer

Applicants who have applied for recruitment jobs need to check BEL Probationary Engineer Exam pattern before your exam preparation. We advise all aspirants to practice BEL previous year papers of your particular discipline like computers, electronics, electrical, mechanical and civil. Online download BEL Probationary Engineer syllabus helps all students to read required materials. Students can able to make out topics from where questions will be given in exam paper.

Applicants who are searching for engineering jobs recently can take advantage of opportunity to build their career in one of Best PSU in India.Even though competition is more for this examination, applicants should study hard and will have to practice well. Luck will not help you all times and preplan well to complete your syllabus before upcoming exam. Download BEL Probationary Engineer syllabus for all ECE, CSE, Mechanical, electrical and civil engineers.

BEL Probationary Engineer Exam pattern 2015

Exam will be conducted in mainly two papers

General Aptitude

Technical Aptitude

Examination is Objective Type. Exam paper is having multiple Choice Questions.

General Aptitude Paper consists of the following

1.      Quantitative Aptitude

2.      Logical Reasoning

3.      General English

4.      General Reasoning

Opening in Bharat Electronics Limited 2015

Recruitment of Probationary Engineers- 2015.

Bharat Electronics Limited is a company which deals with a wide spectrum of products ranging from Radars to Solar based solutions. BEL goes much beyond the defence products they are famous for, they have made inroads into civilian products as well.

There is a requirement for  Probationary Engineers for BEL Units & Offices located in different parts of the country

For graduate Engineer 394 vacancies are  available for Probationary Engineers in BEL.

No of posts are given here :

Electronics -200
Computer Science-57 

Qualification :
Degree holders in Electronics & Communication , Electronics  & Telecommunication, Communication, Telecommunication, Civil Engineering,  Electrical & Electronics Engineering, Mechanical, Computer Science Engineering  disciplines only.  AICTE approved Colleges may only apply. Candidates with AMIE/AMIETE in the above specializations are also eligible, Gen/OBC candidates with first class and SC/ST/PWD candidates with pass in the above degree/discipline are eligible to apply.

Last date to apply the online application : 16/05/2015 

BEL Technical Questions with answers

1. The gray code equivalent of binary 1100 is

a. 1011 b. 1101 c. 1010-and d. 1100

2. A Multiplexer has

a. Multiple inputs and single output

b. Single input and Multiple outputs

c. Multiple inputs and Multiple outputs-ans

d. Multiple inputs for Storage of Data

3. A binary half adder

a. Adds two binary digits and produces their sum and carry-ans

b. Adds half the sum to the carry

c. Adds two binary digits and carry from previous addition

d. Adds two binary digits at half the speed

4. An index register in a computer is for

a. Arithmetic and logic functions

b. Storage of results

c. Modifying the address-ans

d. Counting the no of programmes

5. An example of volatile memory is

a. RAM-ans b. ROM c. EPROM d. Magnetic tape

6. Barrier voltage in a P-N junction is caused by

a. Thermally generated electrons and holes

b. Diffusion of majority carriers across the junction-ans

c. Migration of minority carriers across the junction

d. Flow of drift current

7. The temperature coefficient of an intrinsic semiconductor is

a. Positive b. Negative-ans c. Zero d. Like metals

8. A silicon transistor has a leakage current 1cbo = 1 ma. If the temp. rises by 50o C the leakage current will be

a. 30 ma b. 32ma-ans c. 50ma d. no change

9. The noise figure of an ideal amplifier in decibel is

a. 0.5 b. 0-ans c. 1 d. 10

10. The rise time of an amplifier is 200 nsec. Its bandwidth is

a. 70MHz b. 140MHz c. 100MHz d. 1.75Mhz-ans

11. MOSFET operates in

a. Depletion mode only

b. Enhancement mode only

c. Depletion and enhancement mode-ans

d. None of these of the above

12. A device which behaves like SCRs is

a. UJT b. Triac-ans c. MOSFET d. SRD

13. A plate modulated class C RF amplifier produces 100 KW of radiated power at 100 % modulation. The modulating audio amplifier supplies approximately

a. 25KW b. 33KW-ans c. 50KW d. 66KW

14. A 100 MHz FM carrier, modulated by a 5 KHz sine wave deviates by 50 KHz If the frequency of the modulating sine wave is doubled, the deviation will

a. Double b. Half c. Quadruple d. Have no change-ans

15. Noise generated by a resistor is dependent on

a. Its Value

b. Its temperature

c. Both value and temp-ans

d. None of these

16. A 32 channel 8 bit PCM system samples at 8 KHz rate. The overall bit rate in kilobits per second will be

a. 2048-ans b. 2000 c. 1920 d. 64

17. Stub matching eliminates standing wave on

a. Load side of the stub

b. Source side of the stub

c. Both sides-ans

d. On the stub

18. A half wave folded dipole has a radiation resistance of

a. 72 W b.50W c. 144W d. 288W-ans

19. Top loading is used in antennas for

a. Decrease in impedance

b. Increase in bandwidth

c. Increase in effective height-ans

d. Decease the height

20. The term critical frequency in Ionospheric propagation is

a. Lowest frequency reflected by Ionosphere

b. Highest frequency reflected by the Ionosphere at vertical incidence-ans

c. Lowest frequency reflected by the Ionosphere at vertical incidence

d. Lowest communication frequency possible

21. The cathode ray oscilloscope can be used to measure

a. Frequency b. Time interval c. Voltage d. All the above-as

22. A wein bridge is used for measurement of

a. Resistance b. Capacitance c. Inductance d. Audio frequency-ans

23. The frame rate per second used in India TV is

a. 60 b. 50 c. 25-ans d. 30

24. VHF signals are propagated

a. Via the ionosphere

b. Along the ground-ans

c. Through the troposphere

d. By reflection in ionosphere

25. The impedance of a 3 element yagi antenna is around

a. 75W b. 300W-ans c. 50W d. 100W

26. A PIN diode is microwave

a. Oscillator b. Mixer c. Detector d. Switch-ans

27. A transmission line of VSWR 2 has a reflection coefficient

a. 0.25 b. 0.5 c. 75-ans d. 0

28. Microwave repeaters are typically

a. 25 b. 50-ans c. 75 d. 100 Kms apart

29. To overcome fading in a ship-to-ship communication system we can efficiently use

a. Broadband Antenna

b. Directional Antenna

c. Space Diversity

d. Frequency Diversity-ans

30. Frequency in the UHF range is propagate by waves of

a. Ground b. sky c. Space-ans d. Surface

31. A duplexer is used to

a. Receive two signals in one antenna

b. Prevent interference between two antenna

c. Mix two signals to the same antenna

d. Allow one antenna for both transmission and reception-ans

32. Strapping is used in a magnetron to

a. Prevent mode jumping-ans

b. Reduce frequency drift

c. Ensure proper bunching

d. Dissipate heat

33. A rectangular waveguide behaves like a filter of

a. Band pass b. High pass-ans c. Low pass d. Band stop

34. The signal propagation time in milliseconds for a geosynchronous satellite is

a. 540 b. 270 c. 135-ans d. 100

35. The silicon solar cell is a

a. Photo conductive

b. Photo emissive

c. Photo voltaic-ans

d. Photo resistive

36. For the national TV and ratio network, INSAT-IB uses

a. 400MHz b. 2.5GHz c. 2.5 and 5GHz d. 4 and 6 GHz-ans

37. A typical fibre-optic detector is

a. Step recovery diode

b. Light emitting diode

c. Avalanche photo diode-ans

d. Field effect transistor

38. A modem is a device used for

a. Digitizing voice data

b. Transmission of data on lines

c. Modulating and demodulating signals sent on a line-ans

d. Suppressing noise interference

39. The most effective anti-jamming technique is

a. Frequency hopping-ans

b. Spread Spectrum

c. Frequency synthesis

d. Burst transmission

40. Mono-mode is a term used in

a. Fibre-optics-ans

b. Radar

c. Satellite communication

d. Magnetics

41. Monopulse technique is used in

a. Radar-ans

b. Radio relay

c. Data communication

d. Fibre-optics

42. HDLC is a term for

a. Data communication protocol-ans

b. Synchronizing pulses

c. Gain control in receivers

d. Error checking

43. A gateway

a. Is a place where radars are connected

b. Permits dissimilar networks to communicate-ans

c. Bifurcates the RF path of a transmitter

d. Is a feeder cable

44. Ethernet is a name of

a. Medium of computer communication

b. Network for computer communication-ans

c. Procedures for computer communication network

d. Software for computer communication

45. If several stations in a network want to use a single channel without interfering with one another,

the technique used is called

a. Carrier sense

b. Phantom-freeze

c. Packet switching

d. Multiplexing-ans

46. In a monolithic IC, resistors are formed from

a. Ceramic materials

b. Copper

c. P-type semiconductor-ans

d. Aluminium deposition

47. ICs made by sputtering of materials on a ceramic substrate are called

a. Monolithic b. Hybrid c. Thick film d. Thin film-ans

48. Two coils (inductors) connected in series have a combined inductance of 15mH. When terminals of one of the coils are reversed and connected to the other, the combined inductance is measured to be 9mH. What is the value of mutual inductance

a. 1.5mH b.3mH c.6mH d.12mH

49. If a parallel LC circuit is excited at frequency less than its resonant frequency, the nature of its effective impedance is

a. Resistive b. Inductive c. Capacitive d. None of these of these

50. The wave length of 1 Giga hertz frequency signal is

a. 10cm b. 30cm c. 3cm d. 1cm

51. Which of the following microwave tubes can be considered as broad band devices

a. Magnetrons

b. Klystrons

c. Reflex klystrons

d. Traveling wave tubes[TWT]

52. Which family of the following integrated circuits has the highest speed

a. DTL b. ECL c. TTL d.CMOS

53. The most important feature of CMOS family of ICs is

a. High speed

b. Small size

c. Low power consumption

d. Low input impedance

54. What is the resolution of 8 bit A/D converter if its full scale voltage is 10v

a. 0.02v b. 0.01 c. 0.039v d. 0.078v

55. What value of resistance is to be used in LSB of 4 bit weighted ladder D/A converter if MSB has 10 kW resistor

a. 160k b. 80k c. 240k d. 100k

56. The pulse width of a radar transmitter is 0.6m sec. and the pulse repetition rate is 700 Hz. The average power measured is 420 watts. What is the peak power

a. 100KW b. 420KW c. 1MW d. None of these

57. The device used for isolating the transmitter and receiver in a radar system is called

a. Diplexer

b. Duplexer

c. Directional coupler

d. None of these

58. “Baud” is

a. Total No. of bits/sec in each character

b. Reciprocal of shortest signal element in a character

c. Duration of a character in data transmission

d. None of these

59. The advantage of Totem pole output stage in TTL ICs is

a. Low output impedance

b. Can sink more current

c. Oscillations avoided

d. None of these

60. The capacitance value of a varactor is controlled by

a. A reverse voltage applied to it

b. A series resistance

c. Varying its supply voltage

d. Current through the device


b50. b51. d52. b53. c54. c55. b56. c57. b58. b59. a60. a

61. Electron volt is equivalent to

a. 3.8 * 10-20 erg

b. 1.602 * 10-12 erg

c. 1.602 * 10-18 erg

d. 1.602 * 10-16 erg

62. The kinetic energy of photo electrons emitted by a photo sensitive surface depends on

a. Intensity of the incident radiation

b. Wavelength of the incident radiation

c. Angle of incident of radiation

d. Surface conditions of the surface

63. Flux is expressed in radio-metric system in

a. Lumens

b. Photons

c. Watts

d. Candles

64. In a three-phase bridge rectifier circuit, the ripple frequency is

a. Same as line frequency

b. Twice the line frequency

c. Thrice the line frequency

d. Six times the line frequency

65. Energy stored in a capacitor as a function of voltage is given by

a. CV2

b. 1V2/2C

c. ½ CV2

d. 1V/2C

66. The operational amplifier used in analog computers have usually open loop flat gain approximately upto

a. 1MHz b. 100MHz c. 10MHz d. 0.1MHz

67. An oscillator of 350 MHz is fed with a pulse of rise time 2 n sec. The rise time of the displayed waveform is approximately

a. 1 n sec b. 2.2 n sec c. 2.0 n sec d. 1.7 n sec

68. A radar transmits a peak power of 100 KW with pulse width of 1 m sec and a pulse repetition rate of 100 KHz. The average output power of the radar is

a. 100KW b.10KW c. 1000KW d. 50KW

69. The incremental inductance in a coil is due to

a. Saturation

b. Superimposed DC

c. Mutual inductance

d. Change of frequency

70. Microwave tube based on velocity modulation principle is

a. Klystron

b. Magnetron

c. Light house tube

d. Traveling wave tube


61. b62. b63. a64. b65. c66. d67. c68. b69. d70. a71. a72. a73. b74. a75. b76. a77. b78. a79. a80. b

71. Noise output from the receiver decreases uniformly with noise side band frequency for

a. Frequency modulation

b. Amplitude modulation

c. Pulse amplitude modulation

d. None of these

72. In amplitude modulation the maximum permissible modulation index is

a. Unity b. 100 c. infinity d. None of these

73. In frequency modulation the maximum permissible modulation index is

a. Unity b. 50 c.1000 d. no limit

74. In FM transmission and reception, the pre-emphasis and de-emphasis are used to improve the

a. Signal to noise ratio

b. Frequency response of the receiver

c. Frequency response of the transmitter

d. The sensitivity of the transmitter

75. De-emphasis network uses the combination of

a. R-L b. R-C c. R-L-C d. Transformer

76. The usage of micro sec for defining emphasis is a standard practice but this micro sec definition means

a. 3 dB point of the network means

b. mid point of the network response

c. roll off the network response

d. the stop band ripple of the network response

77. Delayed AGC is applied

a. For all singal strength

b. For singal strength exceeding a specified limit

c. For low singal strength

d. For FM receiver

78. Selectivity means

a. Bandwidth

b. Gain

c. Modulation index

d. None of these

79. Narrow bandwidth broadcast reduces

a. The quality and noise

b. Quality alone

c. Noise alone

d. Quality and intelligibility

80. Squelch means keeping the receiver

a. ON in the absence of carrier

b. OFF in the absence of carrier

c. To remove AGC

d. Increase the AGC

81. Let Z be the series impedance and Y be the shunt admittance of the transmission line, then the characteristic impedance

a. ÖZY b.ÖY/Z c. ÖZ/Y d.All the above

82. Noise figure of an amplifier is defined as

a. Input SNR output SNR

b. Input SNR / output SNR

c. Output SNR / input SNR

d. Input SNR / gain

83. A broadcast radio transmitter radiates 10 KW power when modulation is 60%. Its carrier power will be

a. 8.47KW b.8.92KW c. 8.31KW d.10.00KW

84. In AM transmission antenna current is 8 Ampere at zero modulation indexes but increased to 8.93 Ampere when modulated on single sine wave. Then the % of modulation is approximately

a. 70.1% b. 80.1% c. 65.1% d. 10.0%

85. In AM transmission antenna current is 8 Ampere at zero modulation index. At 80% modulation index the antenna current will be

a. 10.00A b. 8.72A c. 9.19A d. 9.79A

86. If two sine waves are amplitude modulated with modulation index m1 and m2, the effective modulation index is

a. Ö m12/m22

b. Ö m1 m2

c. Ö m12+m22

d. Ö m22/m12

87. If it is transmitted current and Ic is transmitter current at zero modulation index and the transmitted current at modulation index of m will

a. It = Ic Ö[1+m]

b. It = Ic Ö[1+m2]

c. It = Ic Ö[1+m/22]

d. It = IcÖ1+m2

88. If Rr is the radiation resistance and Rd is the lumped resistance, then the antenna efficiency is given

as –

a. (Rr - Rd) / (Rr + Rd)

b. (Rr + Rd) / (Rr – Rd)

c. Rr / (Rr + Rd)

d. Rd / (Rr + Rd)

89. In end fire array, the current

a. Magnitude and phase in each element is the same

b. Magnitude is the same but phase is different in each element

c. Magnitude is different but no phase difference in each element

d. Magnitude and phase are different in each element

90. In a board side array, the current

a. Magnitude and phase in each element is the same

b. Magnitude is the same but phase is different

c. Magnitude is different but no phase difference in each element

d. Magnitude and phase are different in each element

91. Beam width of the 2 metre paraboloid reflector at 6 GHz is

a. 4.5o

b. 9.25o

c. 3.5o

d. 7.75o

92. The cut of wave length for TE m, n mode is in a wave guide of dimension a*b is

a. 2/Ö(m/a)2 +(n/b)2

b. 2Ö [m/a]2 + [n/b]2

c. Ö(m/a)2 + (n/b)2 /2

d. Ö [m/a]2 + [n/b]2

93. For the standard rectangular waveguide dimension of 4*2 cm the off wavelength for TM11 mode is approximately

a. 1.788cm b. 3.576cm c. 1.682cm d. 2.546cm

94. In IMPATT diode, the voltage and current are

a. In phase

b. Out off phase by 90o

c. Out off phase by 180o

d. None of these of the above

95. Which of the following statement is true

a. Tunnel diode & IMPATT diode are negative resistance devices

b. Tunnel diode is positive resistance device and the IMPATT diode is negative resistance device

c. Tunnel diode is negative resistance device and the IMPATT diode is positive resistance device

d. None of these of the above

96. In a SSB modulation system with 100% modulation index the power saving will be

a. 5/6 of carrier power

b. 2/8 of carrier power

c. 5/12 of the carrier power

d. ½ of the carrier power

97. In SSB modulation the modulation index is increased from 0.5 to 1.0, then the power will be increased by

a. 2 times b. 4 times c. 16 times d. 32 times

98. 900 rpm is equal to

a. 94.2 rad/sec

b. 47.1 rad/sec

c. 188.4 rad/sec

d. 16.72 rad/sec

99. Darlington pair is used to

a. Increase the voltage gain

b. Increase the current gain

c. Decrease voltage gain

d. Decrease current gain

100. The transfer function of the system shown is

a. G(s) / {1 + H(s)}

b. G(s) H(s) / {1 + G(s) H(s)}

c. G(s) / {1 + G(s) H(s)} d. G(s) / G(s) H(s)-ans


81. c82. b83. a84. a85. c86. c87. c88. c89. b90. a91. c92. a93. b94. c95. a96. a97. b98. b99. b100. c

BEL Technical and Electronics Paper with Answers


1. Resistivity of silicon in ohms cm. is approx. equal to

a. 50 b. 1012 c. 230k d. 10-6

2. Rsistivity ofGermanium in ohms cm. is approx. equal to

a. 50 b. 10-12 c. 50k d. 10-6

3. The number of free electrons/cubic cm intrinsic Germanium at room temperature is approx. equal to

a. 1.5*1010 b. 2.5*1013 c. 1000 d. 5*106

4. The number of free electrons/cubic cm of intrinsic silicon at room temperature is approx. equal to

a. 1.5*1010 b. 2.5*1013 c. 10000 d. 5*106

5. The forbidden energy gap for silicon is

a. 1.1eV b. 067eV c. 0.97eV d. 1.7eV

6. The forbidden energy gap for Germanium is

a. 1.1eV b. 067eV c. 0.97eV d. 1.7eV

7. N type material is formed by the addition of the following (penta valent )atom in n to semiconductor material

a. Antimony

b. Arsenic

c. Phosphorous

d. Any of the above

8. P type material is formed by the addition of the following [Trivalent] atom tn to semiconductor material

a. Boron b. Gallium c. Indium d. Any of the above

9. Impurity atoms that produces N type material by its addition in semiconductor is called

a. Donar b. Acceptor c. Conductor d. Insulator

10. Impurity atoms that produces P type material by its addition in semiconductor is called

a. Donar b. Acceptor c. Conductor d. Insulator

11. Dynamic resistance of a diode Rd is if voltage changes is DVd and the current change is D Id

a. D Vd / D Id

b. D Id / D Vd

c. 1 / DVd

d. 1 / D Id

12. Point contact diodes are preferred at very high frequency, because of its low junction

a. Capacitance and inductance

b. Inductance

c. Capacitance

13. Identify the circuit given below

a. AND gate

b. OR gate

c. Rectifier

d. NOR gate

14. Identify the circuit given below

a. AND gate

b. OR gate

c. Rectifier

d. NOR gate

15. DC value of a Half wave rectifier with Em as the peak value of the input is

a. 0.318Em

b. 0.418Em

c. 0.518Em

d. 0.618Em

16. Change in Zener voltage of 10V at 100o C if temperature co-efficient is 0.072%o C as

a. 0.54 V b. 0.74 V c. 0.64 V d. 0.14 V

17. If Tc is th e% temperature co of / oC and Vz as zener voltage and T as change in temperature then

the change in zener voltage is

c. 100. Vz. Tc DT

d. None of these of the above

18. PIV for a full wave rectifier, if Em is the peak voltage is

a. Em b. 1.5Em c. 0.636Em d. 2Em

19. Schottky Barrier diodes becomes important at

a. DC level operation

b. Low frequency operation

c. High frequency operation

d. None of these

20. Clamping network is the one that will clamp the signal to a

a. Different peak value

b. Different DC level

c. Different polarity level

d. Different RMS level


1. c2. a3. a4. b5. a6. b7. d8. d9. a10. b11. a12. c13. b14. a15. a16. a17. a18. d19. c20

21. Clipping network is the one that will clip a portion of the

a. Input signal without distorting the remaining portion

b. Input signal with distorting the remaining portion

c. Any of the above

d. None of these

22. Transition capacitance Ct of a Varicap diode with Knee voltage Vt, reverse voltage Vr and K, the

constant based on semiconductor material and the construction technique & N dependent on type of

junction is given by

a. 1 / K (Vt + Vr)N/2

b. 1 / K (Vt + Vr)N

c. K / (Vt + Vr)N

d. K / (Vt + Vr)1/N

23. Ct = K / (Vt + Vr)N where Vt Knee voltage, Vr reverse voltage, K manufacturing dependent constant and N dependent on type of junction, for alloy junction the value of N is

a. 1/3 b. 2/3 c. 1/2 d. 1/4

24. Ct = K / (Vt + Vr)N where Vt Knee voltage, Vr reverse voltage, K manufacturing dependent constant and N dependent on type of junction, for diffused junction the value of N is

a. 1/3 b. 2/3 c. 1/2 d. 1/4

25. In JFET, the drain current Id is given by (Idss drain – source saturation current Vgs – Gate – source voltage, Vp the pinch off voltage)

a. Idss[1 – Vp/Vgs]

b. Idss(1 – Vgs/Vp)2

c. Idss[1 – Vgs/Vp)

d. Idss(1 – Vgs/Vp)3/2

26. The shadow mask in colour tube is used to

a. Reduce X-Ray emission

b. Ensure each beam hits its own dots

c. Increase screen brightness

d. Provide degaussing for the screen

27. Indicate which of the following signal is not transmitted in colour TV

a. Y b. Q c. R d. I

28. Another name for horizontal retrace in TV receiver is the

a. Ringing b. Burst c. Damper d. Fly back

29. Another name for the colour sync in the colour TV system

a. Ringing b. Burst c. Damper d. Fly back

30. The HV anode supply for a picture tube of a TV receiver is generated in the

a. Mains transformer

b. Vertical output stage

c. Horizontal output stage

d. Horizontal oscillator

31. The output of vertical amplifier is

a. Direct current

b. Amplified vertical sync pulse

c. A saw tooth voltage

d. A saw tooth current

32. In a transistor if Alpha = 0.98, current gain is equal to

a. 29 b. 59 c. 69 d. 49

33. The active region in the common emitter configuration means

a. Both collector and emitter junction is reverse biased

b. The collector junction is forward biased and emitter junction

c. The collector junction is reverse biased and emitter junction is forwared biased

d. Both collector & emitter junction are forward biased

34. The saturation region in the common emitter configuration means that

a. Both collector & emitter junction are reverse biased

b. The collector junction is forward biased and emitter junction

c. The collector junction is reverse biased and emitter junction is forwared biased

d. Both collector & emitter junction are forward biased

35. The % of Red, Green & Blue in 100% White Y is given by

a. 30%, 59%, 11%

b. 50%, 30%, 11%

c. 30%, 11%, 50%

d. 33.3%, 33.5%, 38.3%

36. Equalizing pulse width, if H is the Horizontal sync rate

a. 0.64 H b. 0.07 H c. 0.04 H d. 0.16 H

37. In a simple RC network the bandwidth is equal to

a. 1/2 p RC

b. RC / 2

c. 2 C / p R

d. 2 p / RC

38. The time constant of a RC network is given by

a. RC b. C/R c. R/C d. None of these

39. First zero crossing of pulse frequency spectrum occurs at if d is the pulse width, T is the pulse repetition rate

a. 1/d b. d/T c. T/d d. T

40. The distortion less output characteristic of a network means

a. Constant amplitude and linear phase shift over frequency

b. Linear phase shift and amplitude need not be constant

c. Any amplitude and phase

d. None of these

41. Single sideband means suppressed

a. Carrier

b. Carrier and one side band

c. One side band

d. None of these

42. In an amplitude modulated signal, lower side band frequency is equal to (if the carrier frequency is fc and modulation frequency is fm)

a. fm + fc b. fc – fm c. fm r fc d. fc / fm

43. Modulation index of the frequency modulation depends on

a. Amplitude & frequency of the modulation signal

b. Frequency and amplitude of carrier signal

c. Carrier frequency

d. None of these

44. The BW of the narrow band FM if modulating frequency is fm

a. 3 r fm b. 2 r fm c. 2.5 r fm d. 10 r fm

45. Reactance tube modulator is known for

a. FM b. AM c. PPM d. PAM

46. Bandwidth and rise time product is

a. 0.35 b. 0.45 c. 0.30 d. 0.49

47. Energy gap, Lg, for Germanium at room temp [300o K] is

a. 0.72eV b. 1.1eV c. 1.53eV d. 0.2eV

48. Volt equivalent of temperature VT, at 116o K is

a. 0.11V b. 0.01V c. 1.16V d. 0.1V

49. Reverse saturation current of a Ge.diode is in the range of

a. mA b. uA c. nA d. pA

50. Cut-in voltage V for silicon is approximately

a. 0.2V b. 0.6V c. 0.9V d. 1.1V


b21. a22. c23. c24. a25. b26. b27. c28. d29. b30. c31. d32. d33. c34. d35. a36. c37. a38. d39. a40. a41. b42. b43. a44. b45. b46. a47. a48. b49. b50.

51. Every 10o C rise in temp. the reverse saturation current

a. Doubles

b. Halves

c. Triples

d. No change

52. Hall effect with reference to Metal or Semiconductor carrying a current I is placed in a transversemagnetic field B, an electric field E is induced in

a. Parallel to B

b. Perpendicular to I

c. Perpendicular to both B & I

d. Perpendicular to B

53. 1 eV (electron volt) is equal to:

a. 1.9 r 10-20 J

b. 1.6 r 10-19 J

c. 1.6 r 10-20 J

d. 1.16 r 10-19 J

54. Donar impurity is having a valency of:

a. 2 b. 3 c. 4 d. 5

55. Acceptor impurity is having a valency of

a. 2 b. 3 c. 4 d. 5

56. Electron volt arises from the fact that if any electron falls through a potential of 1 volt, its kinetic energy will

a. Decrease, & potential energy will increase

b. Increase & potential energy decrease

c. Be unaltered & potential energy decreases

d. Increase & potential energy increase

57. Hole is created in a semiconductor material if one of following impurities are added

a. Antimony

b. Arsenic

c. Indium

d. Phosphorus

58. Excess electron is created by

a. Boran

b. Gallium

c. Indium

d. Arsenic

59. A snubber circuit is used across the SCR to protect against

a. The di/dt of the anode current

b. The dv/dt turn on

c. L.di/dt of load inductance

d. None of these

60. Germanium has the valency of

a. 2 b. 3 c. 4 d. 5

61. Silicon has the valency of

a. 2 b. 3 c. 4 d. 5

62. Hole acts as a free charge carrier of polarity

a. Negative

b. Positive

c. Neutral

d. None of these

63. Burst signal in NTSC system is 8 cycles of the frequency of

a. Colour sub carrier

b. Picture carrier

c. Sound carrier

d. None of these

64. Colour sub carrier reference burst is superimposed on the

a. Back porch of the each horizontal sync pulse

b. Front porch of the each horizontal sync pulse

c. Front porch of the each vertical sync pulse

d. Back porch of the each vertical sync pulse

65. The law of mass action with reference to semiconductor technology states that the product of free negative & positive concentration is a constant and

a. Independent of amount of donor and acceptor doping

b. Dependent on amount of donor and independent of the amount acceptor impurity doping

c. Depend on amount of both donor & acceptor impurity doping

d. None of these

66. The snubber circuit used across SCR is a simple

a. R-L network

b. RLC network

c. LC network

d. RC network

67. To limit the rate of rise of SCR anode current a small

a. Inductor is inserted in cathode circuit

b. Inductor is inserted in anode circuit

c. Capacitor is inserted in anode circuit

d. Capacitor is inserted in cathode circuit

68. Torque developed by a DC servo motor is proportional to the

a. Product of power and time

b. Product of armature current and back emf

c. Armature voltage and armature current

d. Field voltage and field current

69. Proportional Integral control

a. Reduces steady state error but reduces the forward gain

b. Increases the forward gain and reduces the steady state error

c. Increases the steady state error and increases the forward gain

d. None of these

70. Increasing the servo bandwidth:

a. Improves signal to noise ratio

b. Improves speed response and lowers signal to noise ratio

c. Improves power output

d. None of these


b51. a52. c53. b54. b55. b56. b57. c58. d59. b60. c61. c62. b63. a64. a65. a66. d67. b68. b69. a70. b

71. Notch filter is

a. Low pass filter

b. High pass filter

c. Narrow stop band filter

d. Narrow pass band filter

72. In TV Receivers the Electron beam deflection method used is

a. Electro static

b. Electro magnetic

c. Magnetic

d. All the above

73. In a line of sight communication the maximum range R in miles between the receiver antenna and transmitter antenna of height H in feet is approximately

a. R = 1.93 ÖH

b. R = 1.23 ÖH

c. R = 1.53 ÖH

d. R = 2.03 ÖH

74. In wavelength of the 60 MHz carrier frequency is

a. 10 metres

b. 15 metres

c. 5 metres

d. 2.5 metres

75. In standard TV receiving antenna the dipole element is

a. 0.5 of the wave length

b. 0.25 of the wave length

c. 1.5 of the wave length

d. 1.0 of the wave length

76. The characteristics of FET are similar to:

a. Triode

b. Tertode

c. Pentode

d. Diode

77. Charge coupled device is an array of capacitors whose structure is similar to:

a. Shift register

b. Flip-flop

c. NAND gate

d. Amplifier

78. Operational amplifier characteristics are which of the following:

a. Infinite gain

b. Infinite input impedance

c. Output impedance is zero

d. All of the above

79. The typical value of the open loop gain in dB of an amplifier at DC with no feedback is:

a. 90 to 100

b. 80 to 90

c. 0 to 50

d. 50 to 70

80. The 3 dB band width means the frequency at which

a. The open loop voltage gain reduced to 0.707

b. The open loop gain reduced to unity

c. Maximum voltage of a signal is without distortion

d. It is a medium wave band width of radio receiver

81. Rise time of an amplifier is defined as time required

a. To change from 0 to 100 % of its final value

b. To change from 0 to 50 % of its final value

c. To change from 10 to 90 % of its final value

d. To change from 10 to 100 % of its final value

82. High speed amplifier design emphasized on

a. Extremely small bandwidth

b. Very slow response

c. Unity gain bandwidth after 10 MHz

d. None of these

83. Tuned amplifier having the frequency range between

a. 150 KHz – 50 MHz

b. 100 Hz – 100 KHz

c. 100 KHz – 120 KHz

d. 50 MHz – 100 MHz

84. The resonance frequency of a tuned circuit made up of R, L, C is given by

a. 1/2 pÖLC

b. 2 pÖLC

c. 2 p / ÖLC

d. ÖLC / 2

85. The voltage follower can be obtained using operational amplifier

a. Without any feedback

b. Series parallel feedback of unity

c. Parallel feedback

d. Series feedback

86. Fidelity of the amplifier is when

a. It is a linear amplifier

b. It does not add or subtract any spectral components

c. It amplifier each component by the same amount

d. All of the above

87. What would be the output when two input sine waves of frequency 50 KHz and 100 KHz passed through an amplifier in the medium signal

a. 50 KHz and 100 KHz

b. 100 KHz and 200 KHz

c. 50 KHz and 150 KHz

d. All of the above

88. The important application of Schmitt trigger is

a. To convert slowly varying input voltage to abrupt voltage change

b. To convert abruptly varying input voltage into slowly varying output

c. To change the frequency of the input

d. None of these

89. Meaning of decoding is

a. Binary addition

b. Data transmission

c. Demultiplexing

d. Storage of binary information

90. Approximately how many number of gates are incorporated in SSL chip

a. 12

b. 100

c. Excess of 100

d. Excess of 1000

91. The circuit diagram represents which one of the following

a. Half adder

b. Full adder

c. Exor gate

d. AND gate

92. Flip flop cannot be called as

a. Bistable multivibrator

b. 1 Bit memory unit

c. latch

d. combinational circuit

93. The important use of low pass filter in power supply is

a. To get the regulation in the output voltage

b. To filter out the ripple frequency

c. To increase the current rating

d. To convert AC into DC

94. Binary equivalent of the decimal number 145 is

a. 10010001

b. 1001011

c. 1010001

d. 1100010

95. In which of the following gate the output will be high when all the maintained at high level

a. NOR

b. AND



96. Which of the following definition is true in the De Morgan’s theorem

a. Multiplication symbols are replaced by addition symbol

b. Addition symbols are replaced by Multiplication symbol

c. Each of the terms are expressed in the complementary form

d. All of the above

97. 8421/BCD code fro a decimal number 149 is

a. 0001 0100 1001

b. 10010101

c. 10101001

d. None of these

98. Combinational circuit are mainly characterized by

a. Output depends upon the previous state & presents state

b. Output depends upon the input at that particular instant

c. Output depends upon the presents state & the clock state

d. Output does not depends upon the input at all

99. A flip flop is defined as

a. A bistable device with two complementary outputs

b. It is memory element

c. It will respond to input and it is a basic memory element

d. All of the above

100. Four bit code is called

a. Nibble

b. Byte

c. Word

d. Register


.71. c72. c73. b74. c75. a76. c77. a78. d79. d80. a81. c82. c83. a84. a85. b86. d87. a88. a89. c

90. a91. a92. d93. b94. a5. b96. d97. a98. b9. d100.a

BEL Electronics and Computer Questions with answers

1. The register is a
1. Simplified unit of a subtractor
2. Cascaded group of the flip-flop
3. Binary ripple counter
4. Data selector

2. The energy of the photo electron depends upon the following factor
1. Intensity of incident radiation
2. Quality of the photocathode
3. Frequency of incident radiation
4. Type of the incident light source

3. Hall effect is used to determine
1. Magnetic flux
2. Current density
3. Type of semiconductor material
4. All of the above

4. Which one of the following is the thermistor
1. Semiconductor device
2. Microwave device
3. Platinum resistance thermometer
4. Thermo-couple device

5. Silicon is having direct band gap
1. True
2. False
3. No gap
4. None of these

6. Boron is doped in silicon to form
1. P-type
2. N-type
3. Intrinsic
4. None of these

7. The concentration of impurity in doped silicon semiconductor per atom is
1. 1018 b. 1022 c.108 d.10-22

8. Conduction in P-type semiconductor is due to
1. Movement of hole
2. Movement of electron
3. Movement of atoms
4. Movement of electron-hole pair

9. Slope of electrical conductivity Vs temperature in semiconductor is
1. Positive
2. Negative
3. Linear
4. No effect

10. Volt equivalent of temperature of silicon at room temperature (300 deg K) is
1. 0.7V b. 1.1V c. 0.026V d. 16V


1. b2. c3. d4. d5. a6. a7. a8. a9. b10.

11. Carbon is not used as semiconductor because
1. It does not belong to silicon group
2. It is a good conductor
3. It is not a conductor
4. Band gap is very high

12. In forward bias of P-N junction depletion region
1. Increases
2. Decreases
3. Remains the same
4. Breaks down

13. Knee voltage in diode stands for
1. Reverse break down voltage
2. Saturation voltage
3. Threshold of current conduction
4. Peak inverse voltage

14. An ideal semiconductor diode for an AC input acts like
1. Unidirectional switch
2. Bidirectional switch
3. Cuts off AC part
4. Power booster

15. Reverse saturation current in P-N junction diode is due to
1. Hole conduction
2. Electron conduction
3. Minority carrier conduction
4. Majority carrier conduction

16. In the zener diode the break down in the reverse characteristic current is due to
1. Electrons
2. Hole
3. Electron hole pair
4. Crystal ions

17. The percentage of voltage regulation is defined as
1. V no load " V load r100 / V load
2. V load " V no load r100 / V load
3. V load " V no load r100 / V no load
4. V no load r100 / V load

18. Filtering is effected by shunting the load with a
1. Capacitor
2. Resistor
3. Inductor
4. None of these

19. Without applying the biasing voltage the transistor current would be
1. Maximum
2. Minimum
3. No change
4. Zero

20. In the transistor the doping at the emitter is much larger than the base results in
1. Emitter current entirely of holes
2. Emitter current entirely of electrons
3. Base current is due to electron-hole pair
4. Emitter does contribute carrier which can reach collector
c11. b12. b13. c14. a15. c16. c17. a18. a19. b20.

21. The largest current carrying component in P-N-P transistor is
1. Electrons
2. Holes
3. Electron hole pair
4. Silicon atoms

22. The circuit shown in the figure represents
1. Rectifier
2. Clamping circuit
3. Clipping circuit
4. Low pass filter

23. Clamping circuit is used for
1. AC to DC conversion
2. Biasing
3. Limiting the amplitude
4. Wave shaping

24. For ideal clipping circuit one should use a diode with cut-in voltage
1. 0.7V b.1.1V c. 0V d. 0.2V

25. The ratio of peak inverse voltage of full wave and half wave rectifier is
1. 1 b. 2 c. 1/2 d. 1/4

26. Which of the following transistor configuration is a power amplifier
1. Common emitter
2. Common base
3. Common collector
4. All of the above

27. In a active mode of a transistor, collector conduction takes place due to
1. Majority carrier
2. Minority carrier
3. Common collector
4. All of the above

28. Common emitter configuration is used for a
1. Current amplification
2. Voltage amplification
3. Current and voltage amplification
4. Charge amplification

29. The transistor configuration where input is emitter and output is collector is called:
1. Common emitter
2. Common base common collector
3. Voltage follower(current gain)
30. Beta of a transistor is given by
1. Ib/Ic b. Ic/Ib c. Ib/Ie d. Ic/Ie

b21. b22. b23. c24. b25. a26. d27. a28. c29. b30.

31. Germanium transistor is preferred over silicon transistor in the following application
1. High frequency
2. High power
3. Low voltage
4. Power rectification

32. SCR is based on the principle of
1. Voltage regeneration
2. Current regeneration
3. Power regeneration
4. Power rectification

33. The number of clock pulses arriving at the digital counter input, should be in the form of
1. Decimal
2. Binary
3. Octal
4. Hexadecimal

34. In which of the counter the clock input is common to all flip flops
1. Asynchronous counter
2. Synchronous counter
3. Decade counter
4. Down counter

35. Multiplexer helps in which of the following
1. Repetition of similar circuit construction
2. Selecting all the signal at the output at the same time
3. Prevention of constructing similar circuits
4. Increase in the constructional costs due to repetition circuits

36. Full adder for two inputs can be developed with the help of
1. Two half adder on OR gate
2. One half adder and two OR gate
3. An EXOR gate and AND gate
4. Two AND gates and an OR gate

37. The important use of gray code is for a
1. Ripple counter
2. Full adder
3. Encoder
4. Decoder

38. In which of the code only one bit changes at each time
1. BCD
2. Aiken code
3. Excess 3 code
4. Gray code

39. In Johnson code for N bits, the maximum number can be formed is given by an expression
1. 2.N b. 2N c. 2N " 2N d. None of these
40. The active mode of transistor operation is used in log circuits because of its
1. Non linearity
2. Linearity
3. Switching nature
4. High speed

b31. b32. c33. b34. b35. a 36. a37. c38. d39. b40. a

41. Intermediate frequency in television receiver is
1. 26-46 MHz
2. 1.6-2.3 MHz
3. 455-KHz
4. None of these

42. At absolute temperature, a silicon crystal acts like an insulator because
1. Electrons cannot move through a crystal
2. Electrons are tightly held by other atoms
3. Electrons can break away only by supplying energy
4. All of the above

43. Extrinsic semiconductor is
1. Doped with impurities
2. Exists in the pure state
3. N-type only
4. Only P-type

44. The process of extracting the audio information from the modulated envelope is called
1. Modulation
2. Detection
3. Transmission
4. Oscillation

45. Selectivity of a radio receiver is defined as
1. Ability to reproduce the original frequencies
2. Ability to eliminate wanted frequencies
3. Ability to reject unwanted frequencies
4. Ability to pick up the weak signal

46. Digital counter cannot be used as
1. Clock
2. Timer
3. Event counter
4. Multiplier

47. Distortion in the amplifier is due to
1. Non linearity of the device
2. Inductance presents in the circuits
3. Capacitance
4. Stray effect

48. The purpose of RF amplifier tuning in the radio receiver is
1. To reject all the frequencies
2. To select all the frequencies
3. Only to select required frequencies & amplification
4. To vary the band width

49. The intermediate frequency used in the radio receiver is
1. 455KHz b. 1.6 MHz c. 20 MHz d. 60 MHz

50. The purpose of using tuned circuit between stages in the radio receiver is
1. To increase the selectivity
2. To increase the sensitivity
3. To increase both selectivity and sensitivity
4. To get the detector output

41. d42. d43. a44. b45. c46. d47. a48. c49. a50.

51. In an amplifier, the frequency characteristic may be divided into how many regions
1. Two b. Three c. Four d. Zero

52. Op.amp. has high input impedance because
1. High band width
2. Differential amplifier
3. Current source at input end
4. Common collector configuration

53. Gain of an OP amp. In inverting mode is "Rf / Rn provided, the OP.amp. has
1. Low output impedance
2. Low input bias current
3. High CMRR
4. High open loop gain

54. Slew rate of an
1. Change of O/p voltage with time
2. Propagation speed
3. Input RC time constant
4. Off set voltage drift

55. Instrumentation OP.amp. is used in application where
1. Two instrument are to be interfaced
2. Input is very low level signal
3. DC signals are involved
4. Differential signals are involved

56. An OP.amp. integrater will be
1. Capacitor at input
2. Diode at input
3. Diode feed back
4. Capacitor feed back

57. A logarithmic amplifier will have
1. Inductor feed back
2. Diode feed back
3. Resistance feed back
4. Thermistor feed back

58. OP.amp. can be converted into capacitor by
1. Increasing bandwidth
2. Removing feed back
3. Increasing input impedance
4. Positive feed back

59. Comparators are used as
1. Switching device
2. Linear amplifiers
3. Power amplifiers
4. High speed amplifiers

60. Typical output impedance of 741 OP amps. is
1. 0.5 W b. 1 K W c. 1 W d. 75 W
51. c52. b53. d54. b55. b56. d57. d58. a59. a60. a

61. Typical unity gain bandwidth of 741 OP amps. is
1. 10 MHz b. 100 KHz c. 1 MHz d. 1.5 MHz

62. OP.amp. wein bridge oscillator works when the over all gain is
1. 180 b. 3 c. 1.2 d. 125

63. Important part in a electronic voltage regulator is
1. Error amplifier
2. External pass transistor
3. Reference voltage diode
4. All the above

64. To generate a triangular wave form from a square wave
1. Differentiator is used
2. Integrator is used
3. Logarithmic amplifier is used
4. Clipping circuit is used

65. For multiplying two analog signals which one of the following is used
1. Comparator
2. Hall effect device
3. Gunn diode
4. Tunnel diode

66. Which of the following device is used as an electronic memory element
1. Astable multivibrator
2. Monostable multivibrator
3. Magnetic tape
4. None of these

67. Phase sensitive detector in lock-in-amplifier is used
1. To increase the sensitivity of an instrument
2. To limit the bandwidth
3. To increase the dynamic range of the signal
4. To increase the input impedance

68. In television transmission video signal is
1. Frequency modulated
2. Amplitude modulated
3. Phase modulated
4. delta modulated

69. The Boolean function XYZ + YZ + XZ, after simplification gives
1. X b. Y c. Z d. X+Y+Z
70. Extremely low power dissipation and low cost per gate can be achieved in
1. MOS ICs
3. TTL ICs
4. ECL ICs
c61. a62. b63. d64. b65. a6. c7. b68. b69. c70. b

71. Which of the following digital IC families can give maximum fan-out
1. ECL b. PMOS c. HTL d. CMOS

72. A punched card has
1. 22 rows, 90 columns
2. 12 rows, 80 columns
3. 12 rows, 2 columns
4. 8 rows, 128 columns

73. Which one of the following is a 16 bit microprocessor
1. Zilog 80
2. Intel 8085
3. Motorola 6800
4. Intel 8086

74. (0.3125)10 when converted to base 8 gives
1. (0.16)8 b. (0.26)8 c. (0.24)8 d. (0.124)8

75. Excess " 3 code is a
1. Weighted code
2. Cyclic code
3. Error correcting code
4. Self complementing code

76. ASC II code is a
1. Error detecting code
2. Self correcting code
3. An alphanumeric code
4. A weighted code

77. Modulo " 2 addition is represented by
1. f = XY + XY
2. f = XY + XY
3. f = X + XY
4. f = XY + XZ + YZ

78. Which one of the following Boolean identities is correct?
1. XYZ + YZ + XZ = YZ + XZ
2. XYZ + YZ +XZ = XY + XZ
3. XY +XZ = XY + XZ + YZ
4. X + XY = XY

79. SN7410 IC is a
1. Quad 2 input NAND gate
2. Triple 3 input NAND gate
3. Dual M/S J-K flip flop
4. None of these

80. Intel 8085 microprocessor has two registers known as primary data pointers these are
1. Registers V & C
2. Registers D & E
3. Registers H & L
4. None of these

81. Intel 8080 microprocessor has an instruction set of 91 instructions. The op-code to implement the instruction set should be at least
1. 6 bit b. 7 bytes c. 7 bit d. 8 bit

82. A micro programmed computer can have the following memories in its control memory unit
1. Semiconductor ROM
2. Semiconductor RAM
3. Magnetic RAM
4. None of these

83. In digital circuits parallel operation is preferred because
1. It requires less memory
2. Circuitry is simple
3. It is faster than series operation
4. For None of these of the above reasons

84. SN 7401 IC is a
1. Quad 2 input NAND gate
2. Quad 2 input NAND gate with open collector output
3. Quad single input NAND gate with open collector output
4. None of these

85. What is the binary code of (26)?
1. 11001 b. 10001 c. 11010 d. 10100

86. The basic RS flip flops is
1. A bistable multivibrator
2. A monostable multivibrator
3. An astable multivibrator
4. None of these

87. The input impedance of an operational amplifier is
1. Very small
2. Zero
3. Very high but not infinite
4. Infinite

88. Sn 7411 is
1. OP.amp. monolithic and short circuit protection in-built
2. Two input NAND gate
3. Three input NAND gate with open collector output
4. None of these

89. The output voltage of an operational amplifier is
1. 90 deg out of phase from the input
2. 90 deg out of phase from the input
3. 45 deg out of phase from the input
4. 180deg out of phase from the input
90. The equivalent octal number of (492) is
1. 574 b. 547 c. 754 d. 758

71. d72. b73. d 74. c75. d76. c77. a78. c79. b80. c81. c82. a83. b84. b85. c86. a87. c88. c89. d90. c

91. The equivalent decimal number for gray code 1011 is
1. 14 b. 13 c. 41 d. 31

92. The output will be only if all inputs go to 1 in case of
1. OR gate b. AND gate c. NAND gate d. NOT gate

93. Which of the following circuits is known as half adder?
1. AND circuit
2. OR circuit
3. Exclusive OR circuit
4. None of these

94. Which of the following memories is used to store variable quantities of the data?
1. RAM b. ROM c. PROM d. EPROM

95. Large scale Integrated (LSI) circuits usually contain
1. Less than 10 gates
2. 10 to 100 gates
3. more than 100 gates
4. more than 1000 gates

96. The Boolean expression A + AB + B on simplification can be reduced to:
1. 0 b. 1 c. A + B d. A + B

97. For realizing a decade counter using flip-flops the minimum number of flip-flops required is
1. 4 b. 5 c. 6 d. 10

98. Which logic family is widely used in SSI & MSI applications?
1. ECL b. DTL c. TTL d. None of these

99. An amplitude modulation detector detects
1. The peak value of the modulation signal
2. The envelop of the modulation signal
3. The peak value of the carrier signal
4. The average value of the carrier signal

100. Microwave (MW) links are generally preferred to coaxial cable for TV transmission because:
1. They have less overall phase distortion
2. They are cheaper
3. Of their greater bandwidth
4. Of their relative immunity to impulse noise.
91. b92. b93. c94. a95. c96. b97. a98. c99. b100. a