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BEL Placement Paper : BEL Placement Paper Technical Electronics 23 December 2011

BEL Probationary Engineer(Mechanical) Written Test Questions

BEL Technical Questions

1. Newton’s law of viscosity relates
A. Velocity gradient and rate of shear strain
B. Rate of shear deformation and shear stress
C. Shear deformation and shear stress
D. Pressure and volumetric strain
Ans: B

2. Calculation of meta-centric height of a floating body involves second moment of area.The axis about which this moment is to be calculated passes through the
A. Top horizontal surface of the body
B. Bottom horizontal surface of the body
C. Centre of gravity of the body
D. Centre of buoyancy
Ans: B

3. The buoyancy force is
A. Equal to volume of liquid displaced
B. Force necessary to maintain equilibrium of a submerged body
C. The resultant force acting on a floating body
D. The resultant force on a body due to the fluid surrounding it
Ans: D

4. Navier – stokes equations are useful in the analysis of
A. Turbulent flows
B. Vortex flows
C. Viscous flows
D. Rotatioal flows
Ans:C

5. When air is adiabatically saturated, the temperature attained is the
A. Dew point temperature
B. Dry bulb temperature
C. Wet bulb temperature
D. Apparatus Dew-point temperature
Ans: C

6. Air vessels are used in reciprocating pumps in order to
A. Increase the delivery head
B. Reduce suction head
C. Minimize delivery head fluctuation
D. Reduce accelerating head
Ans: D

7. A Kaplan turbine is a
A. Outward flow reaction turbine
B. Inward flow impulse turbine
C. Low head axial flow turbine
D. High head mixed flow turbine
Ans: C

8. Clapeyron’s equation is used for finding out the
A. Dryness fraction of steam only
B. Entropy of superheater vapour only
C. Specific volume at any temperature and pressure
D. Total heat of superheated steam only
Ans: C

9. In a single stage reciprocating air compressor, the work done on air to compress it from
suction pressure to delivery pressure will be minimum when the compression is
A. Isothermal process
B. Adiabatic process
C. Polytropic process
D. Constant pressure process
Ans: A

10. The function of economizer in a boiler is to
A. Superheat the steam
B. Reduce fuel consumption
C. Increase steam pressure
D. Maintain saturation temperature
Ans: B

11. Which one of the following represents open thermodynamic system?
A. Manual ice cream freezer
B. Centrifugal pump
C. Pressure cooker
D. Bomb calorimeter
Ans:B

12. Isentropic flow is
A. Irreversible adiabatic flow
B. Reversible adiabatic flow
C. Ideal fluid flow
D. Frictionless reversible flow
Ans: B

14. Lowest COP is of vapour
A.Compression cycle with superheated vapour
B. Compression cycle with dry compression
C. Compression cycle with wet compression
D. Absorption cycle
Ans: D

15. Air injection is IC engine refers to injection of
A. Air only
B. Liquid fuel only
C. liquid fuel and air
D. Supercharging air
Ans: B

16. In the SI engine, highest UBHC concentration is observed during
A. Maximum load
B. Acceleration
C. Deceleration
D. Idling
Ans: D

17. In the film established along a vertical plate during condensation of any vapour over the
plates, the temperature distribution curve is
A. Concave upwards
B. Concave downwards
C. Parabolic
D. Straight line
Ans: D

18. Ice is very close to a
A. Gray body
B. Black body
C. White body
D. Specular body
Ans: B

19. Which of the following is not an essential component of any refrigeration system, where refrigeration effect is produced by vaporization of refrigerant ?
A. Compressor
B. condenser
C.Evaporator
D. Expansion device
Ans: A

20. The centre of pressure for an inclined surface area
A. Lies below the centroid of the surface strain
B. Coincides with the centroid
C. Lies above the centroid of the surface
D. None of the above
Ans: (a)

BEL General Aptitude

1. The total number of digits used in numbering the pages of a book having 366 pages is
A. 732
B. 990
C.1098
D.1305
Ans:B
Explanation: Total number of digits= (No. of digits in 1- digit page nos. + No. of digits in 2-digit page nos. + No. of digits in 3- digit page nos.)
= (1 x 9 + 2 x 90 + 3 x 267) = (9 + 180 + 801) = 990

2. A and B together can do a piece of work in 30 days. A having worked for 16 days, B finishes the remaining work alone in 44 days. In how many days shall B finish the whole work alone?

A.30 days
B. 40 days
C. 60 days
D. 70 days
Ans:C

3. 39% of a number exceeds 19% of the same by 48. What is the number ?
A.180
B. 260
C. 240
D. 280
Ans:C

4. (√5+√3)/(√5-√3) is equal to :
A. 1
B. 2
C. 4-√15
D. 4+√15
Ans:C

5. A is the son of C; C and Q are sisters; Z is the mother of Q and P is the son of Z. Which of the following statements is true?
A. P and A are cousins
B. P is the maternal uncle of A
C. Q is the maternal grandfather of A
D. C and P are sisters
Ans:B

Explanation: C and Q are sisters and A is the son of C. Hence, C is the mother of A or Z is the mother Q.Hence, Z is the maternal grandmother of A. P is the son of Z. Hence, P is the maternal uncle of

6. QAR, RAS, SAT, TAU, _____
A. UAV
B. UAT
C. TAS
D. TAT
Ans:A
Explanation: In this series, the third letter is repeated as the first letter of the next segment. The middle letter, A, remains static. The third letters are in alphabetical order, beginning with R.

7. .”School” is related to “Education” in the same way as “court” is related to
A. Lawyer
B. Criminal
C. Justice
D.Jugde
Ans:C

8. The sum of the first 47 terms of the series 1/4+1/5-1/6-1/4-1/5+1/6+1/4+1/5-1/6… is:
A. 0
B. –(1/6)
C. 1/6
D. 1
Ans:B

9. The smallest value of m, for which 2m+1 is not a prime number, is:
A. 3
B. 4
C. 5
D. 6
Ans:B

10. How big will an angle of one and a half degree look through a glass that magnifies things three times?
A. 1 ½
B. 2 ½
C.3 ½
D. 4 ½
Ans: A. 1 ½ degrees
Explanation : The magnifying glass cannot increase the magnitude of an angle.

11. Nitin,s age was equal to square of some number last year and the following year it would be cube of a number. If again Nitin,s age has to be equal to the cube of some number, then for how long he will have to wait?
A. 10
B. 38
C. 39
D. 64
Ans:B
Explanation: Clearly, we have to first find two numbers whose difference is 2 and of which the smaller one is a perfect square and the bigger one a perfect cube.
Such numbers are 25 and 27.
Thus, Nitin is now 26 years old. Since the next perfect cube after 27 is 64,
so required time period = (64 - 26) years = 38 years.

12. 1, 6, 24, 60,120, 210
A. 336
B. 366
C. 330
D. 660
Ans: A. 336

13. A cylindrical container has a radius of eight inches with a height of three inches. Compute how many inches should be added to either the radius or height to give the same increase in volume?
A. 13
B. 16/3
C. 11/3
D. 17/3

Ans: B.16/3 inches

Explanation : Let x be the amount of increase. The volume will increase by the same amount if the radius increased or the height is increased.
So, the effect on increasing height is equal to the effect on increasing the radius.
i.e., (22/7)*8*8*(3+x) = (22/7)*(8+x)*(8+x)*3
Solving the quadratic equation we get the x = 0 or 16/3. The possible increase would be by 16/3 inches.

14. 12 men take 36 days to do a work while 12 women complete 3/4 th of the same work in 36 days.In how many days 10 men and 8 women together will complete the same work?
A. 6
B. 27
C. 12
D. Data inadequate
Ans:B

15.If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is:
A. 53.33
B. 54.68
C. 55
D. None of these
Ans:B

BEL Placement Paper : BEL Placement Paper Technical 23 Dec 2011



Bel upcoming electrical, mechanical apprentice engineering written test syllabus, solved question papers model,bel aptitude reasoning general knowledge and general awareness, current affairs, technical and engineering questions, Bel latest 2010,2011,2012,2013 sample placement papers Bel syllabus, previous years question papers with solutions, Bel probationary engineering technical support technical interview questions Bel Electrical Engineering Objective Questions, Bel computer engineering, probationary engineering,Bel management trainee-MT questions BEL Placement Paper (Technical-Electronics-IVth)| 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

Answer

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
Answers
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

Answers
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
Answers

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

Answers
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 OP.amp.is
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
Answers
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
2. CMOS ICs
3. TTL ICs
4. ECL ICs
Answers
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


Answers
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

BEL Placement Paper : BEL Placement Paper Latest 23 December 2011

Bel Electrical Engineering Objective Questions
1. Capacitive reactance for single­phase series a.c circuit is


2. Which one of the following test used for testing dc machines
a) Short­circuit test
b) Back to Back test
c) Brake Test
d) All of the above

3. If transformer secondary is open, which draw some current is known as
a) Secondary current
b) no­load primary current
c) no­load secondary current
d) None of the above

4. If the generator bearings is hot the reason is
a) eddy current
b) Operation at low speed
c) Less oil
d) None of the above

5. Which one of the following is p­type impurities
a) Phosphorus
b) Aluminium
c) Antimony
d) None of the above

6.Which one of the following is a parts of centrifugal pump
a) Draft tube
b) Breaking jet
c) Impeller
d) All of the above

7. Chopper used to convert
a) Constant dc voltage in to variable dc voltage
b) DC power in to AC power
c) AC power in to DC power
d) None of the above

8. What are the input, output terminal of a transistor in common base circuit configuration
a) Base ­ Input, Collector ­ Output
b) Emitter ­ Input, Collector ­ Output
c) Collector ­ Input, Emitter ­ Output
d) None of the above

9. Common ­ collector amplifier is also called
a) Emitter Follower
b) Register
c) Voltage Regulator
d) None of the above

10. Silicon controlled switch is a
a) 4 ­ terminal PNPN device
b) 4 ­ layer PNPN device
c) 3 ­ layer, 3 terminal PNPN device
d) a & b are correct

11. A tunnel diode is used for
a) Pulse generator
b) Square wave generator
c) Microwave frequencies
d) None of the above
12. Density of fluid is defined as the ratio of

13. Which one of the following device used to measure pressure of a fluid
a) Venturimeter
b) Orifice meter
c) Manometers
d) pitot ­ tube

14. Hydraulic machines which converts
a) hydraulic in to mechanical energy
b) Mechanical energy in to hydraulic energy
c) Mechanical energy in to electrical energy
d) None of the above

16. Shunt­wound Generators (self­excited) used for
a) Boosters
b) Charging Batteries
c) a & b are correct
d) None of the above.

17. If a generator gives spark on commutator the reason is
a) Overload
b) Armature Shortcircuit
c) a & b are correct
d) None of the above

18 The equipment required for protection of transformers.
a) Breather
b) Conservator
c) Emergency release
d) Temperature Gauge
e) All of the above

19. Why flux is used for soldering?
a) To remove oxides from the surface to be soldered
b) it is used as a paste
c) without flux cannot solder
d) None of the above

20. Empire cloth is used for
a) Overhead lines
b) switches
c) Insulating the machines while winding
d) None of the above

21. Thermal efficiency is defined as the ratio of
a) Output Energy / Input Energy
b) (Output Energy / Input Energy) x 100
c) Useful heat / Total heat
d) (Useful heat / Total heat) x 100

22. Moving iron attraction type meter used for
a) Measure current in A.C
b) Measure current in D.C
c) a & b are correct
d) None of the above

23. Moving coil instrument used in
a) ac only
b) dc only
c) both ac & dc
d) None of the above

24. Fluorescent lamp circuit is a
a) Series Circuit
b) Parallel Circuit
c) Combination of series & Parallel Circuit
d) None of the above

25. In Fluorescent lamp circuit why choke is used
a) it gives low Voltage impulse for starting lamp
b) It gives high Voltage impulse for starting lamp
c) It prevent the lamp from overvoltages
d) it acts as a stabillizer

26. Alternators are rated in
a) KW b) KVA
c) KVAR
d) None of the above

27. The inverse of reluctance is called
a) Permence
b) Permittance
c) Saturation
d) None of the above

28 . Ci rcul ati ng current protecti on scheme used i n
a) busbar Answer
b) Transformer
c) Feeder
d) None of the above

29. Ti me -graded protecti on scheme used i n
a) busbar
b) Transformer
c) Feeder Answer
d) Transmi ssi on l i ne

30. Carri er current protecti on scheme used i n
a) Busbar
b) Transformer
c) Feeder Answer
d) Reactor

31. FET i s a
a) Bi pol ar devi ce
b) Uni pol ar devi ceAnswer
c) Curent Control l ed devi ce
d) None of the above

32. BJT i s a
a) Uni pol ar devi ce
b) Vol tage control l ed devi ce-
c) Bi pol ar devi ce -Answer
d) None of the above

33. Current carri er hol es are el ectrons for
a) N Channel JFET -Answer
b) P Channel JFET
c) a & b are correct
d) None of the above

34. I n Enhancement mode the MOSFET operates when
a) Gate vol tage i s negati ve
b) Drai n vol tage i s negati ve
c) Source Vol tage i s posi ti ve
d) Gate vol tage i s posi ti ve-Answer

35. MOSFET operates i n
a) onl y i n enhancement method
b) onl y i n depl eti on method
c) a and b are correct-Answer
d) None of the above

36. Power MOSFET i s a
a) Current control l ed devi ce
b) Vol tage control l ed devi ce-Answer
c) a & b are correct
d) none of the above

37. FET i s a
a) Bi pol ar devi ce
b) Current control l ed devi ce-Answer
c)Three termi nal semi conductor devi ce
d) none of the above

38 . Zener di ode i s a
a) Vol tage regul ator di ode
b) Breakdown di ode
c) Current regul ator di ode-Answer
d) a and b are correct

39. Epi taxi al growth method used i n
a) I C Fabri cati on -Answer
b) MOSFET Fabri cati on
c) BJT Fabri cati on
d) None of the above

40Di stance Rel ays operates when
a) The rati o V/I i s l ess than a predetermi ned val ue-Answer
b) The rati o V/I i s hi gher than a predetermi ned
c) a and b are correct
d) None of the above

BEL Placement Paper : BEL Placement Paper 23 December 2011

BEL Technical Questions
1. Data will remain intact even when the computer is turned off, if it is stored on ..............
A.RAM
B.motherboard
C.secondary storage device
D.primary storage device
Ans.C

2. A(n) .............. converts and executes one statement at a time.
A.compiler
B.instructor
C.converter
D.interpreter
Ans.D

3. A .............. is equipment that might be added to a computer to enhance its functionality.
A.digital device
B.system add-on
C.disk pack
D.peripheral device
Ans.D

4. Approximately how many bytes make one megabyte?
A.One thousand
B.Ten thousand
C.One hundred
D.One million
Ans.D

5. Fax machines and imaging systems are examples of:
A.bar-code readers
B.imaging systems
C.scanning devices
D.pen-based systems
Ans.B

6. A compiler which runs on one machine and produces target code for another is called a:
A.Bootstrapping compiler
B.Just-in-time compiler
C.Cross compiler
D.Optimizing compiler
Ans.C

7. The maximum length (in bytes) of an IP packet:
A.255
B.1023
C.32767
D.65535
Ans.D

8. The degree of multiprogramming is controlled primarily by?
A.Short-term scheduler
B.Medium-term scheduler
C.Long-term scheduler
D.Disk scheduler
Ans.C

9. The microchip that controls a computer’s interface to its attached serialdevices is:
A.Virtual Device driver
B.Universal Asynchronous Receiver/Transmitter
C.Serial presence detect
D.Bus master
Ans.B

10. Which was the first processor to be shipped with a 1 gigahertz clock speed?
A.Athlon
B.BeOS
C.Crusoe
D. Pentium
Ans.A

11. A group of microchips designed to work as a unit to perform one or more related functions is called:
A.Biochip
B.Bus
C.Chipset
D.Diode
Ans.C

12. Who developed the concept of semaphores?
A.Dekker
B.Tanenbaum
C.Kruskal
D.Dijkstra
Ans.D

13. In laser printing, there are six steps the printer follows. What comes between the conditioning phase and the developing phase?
A. transfer phase
B. writing phase
C. fusing phase
D. cleaning phase
Ans:B

14. A process known as ____________ is used by large retailers to study trends
A. data mining
B. data selection
C. POS
D. data conversion
Ans:A

15. ____________ is the science that attempts to produce machines that display the same type of intelligence that humans do.
A. Nanoscience
B. Nanotechnology
C. Simulation
D. Artificial intelligence (AI)
Ans:D
16. Computers process data into information by working exclusively with
A. multimedia.
B. words
C. characters.
D. numbers
Ans:D

17. A string of eight 0s and 1s is called a
A. megabyte.
B. byte.
C. kilobyte.
D. gigabyte
Ans:B

18. The components that process data are located in the
A. input devices
B. output devices.
C. system unit.
D. storage component.
Ans:C

19. Word processing, spreadsheet, and photo-editing are examples of:
A. application software.
B. system software
C. operating system software
D. platform software.
Ans:A

20. Apple Macintoshes (Macs) and PCs use different ____________ to process data and differentoperating systems
A. languages
B. methods
C. CPUs
D. storage devices
Ans:C

BEL General Aptitude
1. The sum of the first 47 terms of the series 1/4+1/5-1/6-1/4-1/5+1/6+1/4+1/5-1/6… is:
A. 0
B. –(1/6)
C. 1/6
D. 1
Ans:B

2. (√5+√3)/(√5-√3) is equal to :
A. 1
B. 2
C. 4-√15
D. 4+√15
Ans:C

3. The smallest value of m, for which 2m+1 is not a prime number, is:
A. 3
B. 4
C. 5
D. 6
Ans:B

4. How big will an angle of one and a half degree look through a glass that magnifies things three times?
A. 1 ½
B. 2 ½
C.3 ½
D. 4 ½
Ans: A. 1 ½ degrees
Explanation : The magnifying glass cannot increase the magnitude of an angle.

5. 1, 6, 24, 60,120, 210
A. 336
B. 366
C. 330
D. 660
Ans: A. 336

6. A cylindrical container has a radius of eight inches with a height of three inches. Compute how many inches should be added to either the radius or height to give the same increase in volume?
A. 13
B. 16/3
C. 11/3
D. 17/3
Ans: B.16/3 inches
Explanation : Let x be the amount of increase. The volume will increase by the same amount if the radius increased or the height is increased.
So, the effect on increasing height is equal to the effect on increasing the radius.
i.e., (22/7)*8*8*(3+x) = (22/7)*(8+x)*(8+x)*3
Solving the quadratic equation we get the x = 0 or 16/3. The possible increase would be by 16/3 inches.

7. 12 men take 36 days to do a work while 12 women complete 3/4 th of the same work in 36 days.In how many days 10 men and 8 women together will complete the same work?
A. 6
B. 27
C. 12
D. Data inadequate
Ans:B

8. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is:
A. 53.33
B. 54.68
C. 55
D. None of these
Ans:B

9. A is the son of C; C and Q are sisters; Z is the mother of Q and P is the son of Z. Which of the following statements is true?
A. P and A are cousins
B. P is the maternal uncle of A
C. Q is the maternal grandfather of A
D. C and P are sisters
Ans:B

10. 39% of a number exceeds 19% of the same by 48. What is the number ?
A.180
B. 260
C. 240
D. 280
Ans:C

11. The total number of digits used in numbering the pages of a book having 366 pages is
A. 732
B. 990
C.1098
D.1305
Ans:B
Explanation: Total number of digits= (No. of digits in 1- digit page nos. + No. of digits in 2-digit page nos. + No. of digits in 3- digit page nos.)
= (1 x 9 + 2 x 90 + 3 x 267) = (9 + 180 + 801) = 990

12. QAR, RAS, SAT, TAU, _____
A. UAV
B. UAT
C. TAS
D. TAT
Ans:A
Explanation: In this series, the third letter is repeated as the first letter of the next segment. The middle letter, A, remains static. The third letters are in alphabetical order, beginning with R.

13. ”School” is related to “Education” in the same way as “court” is related to
A. Lawyer
B. Criminal
C. Justice
D.Jugde
Ans:C

14. Nitin,s age was equal to square of some number last year and the following year it would be cube of a number. If again Nitin,s age has to be equal to the cube of some number, then for how long he will have to wait?
A. 10
B. 38
C. 39
D. 64
Ans:B
Explanation: Clearly, we have to first find two numbers whose difference is 2 and of which the smaller one is a perfect square and the bigger one a perfect cube.
Such numbers are 25 and 27.
Thus, Nitin is now 26 years old. Since the next perfect cube after 27 is 64,
so required time period = (64 - 26) years = 38 years.

15. A and B together can do a piece of work in 30 days. A having worked for 16 days, B finishes the remaining work alone in 44 days. In how many days shall B finish the whole work alone?
A.30 days
B. 40 days
C. 60 days
D. 70 days
Ans:C

BEL Placement Paper : BEL Placement Paper Technical 23 December 2011

BEL Probationary Engineer(Computer Science) Written Test Questions

BEL Technical Questions
1. Data will remain intact even when the computer is turned off, if it is stored on ..............
A.RAM
B.motherboard
C.secondary storage device
D.primary storage device
Ans.C

2. A(n) .............. converts and executes one statement at a time.
A.compiler
B.instructor
C.converter
D.interpreter
Ans.D

3. A .............. is equipment that might be added to a computer to enhance its functionality.
A.digital device
B.system add-on
C.disk pack
D.peripheral device
Ans.D

4. Approximately how many bytes make one megabyte?
A.One thousand
B.Ten thousand
C.One hundred
D.One million
Ans.D

5. Fax machines and imaging systems are examples of:
A.bar-code readers
B.imaging systems
C.scanning devices
D.pen-based systems
Ans.B

6. A compiler which runs on one machine and produces target code for another is called a:
A.Bootstrapping compiler
B.Just-in-time compiler
C.Cross compiler
D.Optimizing compiler
Ans.C

7. The maximum length (in bytes) of an IP packet:
A.255
B.1023
C.32767
D.65535
Ans.D

8. The degree of multiprogramming is controlled primarily by?
A.Short-term scheduler
B.Medium-term scheduler
C.Long-term scheduler
D.Disk scheduler
Ans.C

9. The microchip that controls a computer’s interface to its attached serialdevices is:
A.Virtual Device driver
B.Universal Asynchronous Receiver/Transmitter
C.Serial presence detect
D.Bus master
Ans.B

10. Which was the first processor to be shipped with a 1 gigahertz clock speed?
A.Athlon
B.BeOS
C.Crusoe
D. Pentium
Ans.A

11. A group of microchips designed to work as a unit to perform one or more related functions is called:
A.Biochip
B.Bus
C.Chipset
D.Diode
Ans.C

12. Who developed the concept of semaphores?
A.Dekker
B.Tanenbaum
C.Kruskal
D.Dijkstra
Ans.D

13. In laser printing, there are six steps the printer follows. What comes between the conditioning phase and the developing phase?
A. transfer phase
B. writing phase
C. fusing phase
D. cleaning phase
Ans:B

14. A process known as ____________ is used by large retailers to study trends
A. data mining
B. data selection
C. POS
D. data conversion
Ans:A

15. ____________ is the science that attempts to produce machines that display the same type of intelligence that humans do.
A. Nanoscience
B. Nanotechnology
C. Simulation
D. Artificial intelligence (AI)
Ans:D
16. Computers process data into information by working exclusively with
A. multimedia.
B. words
C. characters.
D. numbers
Ans:D

17. A string of eight 0s and 1s is called a
A. megabyte.
B. byte.
C. kilobyte.
D. gigabyte
Ans:B

18. The components that process data are located in the
A. input devices
B. output devices.
C. system unit.
D. storage component.
Ans:C

19. Word processing, spreadsheet, and photo-editing are examples of:
A. application software.
B. system software
C. operating system software
D. platform software.
Ans:A

20. Apple Macintoshes (Macs) and PCs use different ____________ to process data and differentoperating systems
A. languages
B. methods
C. CPUs
D. storage devices
Ans:C

BEL General Aptitude
1. The sum of the first 47 terms of the series 1/4+1/5-1/6-1/4-1/5+1/6+1/4+1/5-1/6… is:
A. 0
B. –(1/6)
C. 1/6
D. 1
Ans:B

2. (√5+√3)/(√5-√3) is equal to :
A. 1
B. 2
C. 4-√15
D. 4+√15
Ans:C

3. The smallest value of m, for which 2m+1 is not a prime number, is:
A. 3
B. 4
C. 5
D. 6
Ans:B

4. How big will an angle of one and a half degree look through a glass that magnifies things three times?
A. 1 ½
B. 2 ½
C.3 ½
D. 4 ½
Ans: A. 1 ½ degrees
Explanation : The magnifying glass cannot increase the magnitude of an angle.

5. 1, 6, 24, 60,120, 210
A. 336
B. 366
C. 330
D. 660
Ans: A. 336

6. A cylindrical container has a radius of eight inches with a height of three inches. Compute how many inches should be added to either the radius or height to give the same increase in volume?
A. 13
B. 16/3
C. 11/3
D. 17/3
Ans: B.16/3 inches
Explanation : Let x be the amount of increase. The volume will increase by the same amount if the radius increased or the height is increased.
So, the effect on increasing height is equal to the effect on increasing the radius.
i.e., (22/7)*8*8*(3+x) = (22/7)*(8+x)*(8+x)*3
Solving the quadratic equation we get the x = 0 or 16/3. The possible increase would be by 16/3 inches.

7. 12 men take 36 days to do a work while 12 women complete 3/4 th of the same work in 36 days.In how many days 10 men and 8 women together will complete the same work?
A. 6
B. 27
C. 12
D. Data inadequate
Ans:B

8. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is:
A. 53.33
B. 54.68
C. 55
D. None of these
Ans:B

9. A is the son of C; C and Q are sisters; Z is the mother of Q and P is the son of Z. Which of the following statements is true?
A. P and A are cousins
B. P is the maternal uncle of A
C. Q is the maternal grandfather of A
D. C and P are sisters
Ans:B

10. 39% of a number exceeds 19% of the same by 48. What is the number ?
A.180
B. 260
C. 240
D. 280
Ans:C

11. The total number of digits used in numbering the pages of a book having 366 pages is
A. 732
B. 990
C.1098
D.1305
Ans:B
Explanation: Total number of digits= (No. of digits in 1- digit page nos. + No. of digits in 2-digit page nos. + No. of digits in 3- digit page nos.)
= (1 x 9 + 2 x 90 + 3 x 267) = (9 + 180 + 801) = 990

12. QAR, RAS, SAT, TAU, _____
A. UAV
B. UAT
C. TAS
D. TAT
Ans:A
Explanation: In this series, the third letter is repeated as the first letter of the next segment. The middle letter, A, remains static. The third letters are in alphabetical order, beginning with R.

13. ”School” is related to “Education” in the same way as “court” is related to
A. Lawyer
B. Criminal
C. Justice
D.Jugde
Ans:C

14. Nitin,s age was equal to square of some number last year and the following year it would be cube of a number. If again Nitin,s age has to be equal to the cube of some number, then for how long he will have to wait?
A. 10
B. 38
C. 39
D. 64
Ans:B
Explanation: Clearly, we have to first find two numbers whose difference is 2 and of which the smaller one is a perfect square and the bigger one a perfect cube.
Such numbers are 25 and 27.
Thus, Nitin is now 26 years old. Since the next perfect cube after 27 is 64,
so required time period = (64 - 26) years = 38 years.

15. A and B together can do a piece of work in 30 days. A having worked for 16 days, B finishes the remaining work alone in 44 days. In how many days shall B finish the whole work alone?
A.30 days
B. 40 days
C. 60 days
D. 70 days
Ans:C

BEL Placement Paper : BEL Placement Paper Technical Other 23 December 2011

BEL Placement Paper Technical-Electronics Questions and 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

Answers

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



Answers

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

Answers

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

BEL Placement Paper : BEL Placement Paper Hyderabad 21 Oct 2011

BEL Placement Paper Questions with answers| BEL Latest Written Test Questions



2011 BEL Placement Paper:-



1. In which of the following movements ‘Vande Mataram’ was adotped for the first time as a slogan for agitation?



(A) Revolt of 1857

(B) Partition of Bengal in 1905

(C) Non-cooperation Movement in 1922

(D) Quit India Movement in 1942



2. Who warned Gandhiji not to encourage fanaticism of Muslim religious leaders and their followers?



(A) Agha Khan

(B) AjmaI Khan

(C) Hasan Imam

(D) Mohammad Ali Jinnah



3. Which one of the following is not correct about the Congress Session.of Lucknow, 1916?



(A) Ambika Charan Majumdar was not the president of this session

(B) In this session the reunion between the liberal and the extremist was established

(C) Mahatma was apprised the problems of the peasants Champaran for the first time

(D) None of the above



4. Kanpur conspiracy case was against the leaders of?



(A) Khilafat Movement

(B) Non-cooperation Movement

(C) Communist Movement

(D) Revolutionary Movement



5. In India “Currency Notes issue system” is based on?



(A) Minimum reserve system

(B) Proportional reserve system

(C) Fixed exchange rate system

(D) Full convertibility system



6. ‘Disguised’ unemployment means?



(A) Persons with no jobs

(B) Unemployment among house wives

(C) Unemployment among per sons above 60 years pf age

(D) Employment of more persons in a job which lesser number of persons can perform



7. Which of the following statements are true about the income tax in India?



1. It is a progressive tax,

2. It is a direct tax.

3. It is collected by the Government.

4. It is a proportional tax Select the correct answer from the code given below



Codes:

(A) 1 only

(B) 1 and 2 only

(C) 1,2and3only

(D) 2, 3 and 4 only



8. ‘SIDBI’ has been established to-



(A) Finance small scale industries

(B) Finance cottage industries

(C) Finance large scale industries

(D) Finance public sector under takings



9. Gangubai Hangal, who died a few months ago, was a?



(A) Classical singer

(B) Dancer

(C) Painter

(D) Sitar player



10. Deep Joshi has recently been given Raman Magsaysay Award in the category of?



(A) Government service

(B) Public service

(C) Community leadership

(D) Emergent leadership



11. The missing number in the following series: 5,10,13,26,29, 58, 61,…Is?



(A) 122

(C) 128

(B) 125

(D) 131



12. If 2 jeans and 3 shirts cost Rs. 4,000 and jeans and 2 shirts cost Rs. 3,500, how much does a jeans cost?



(A) Rs. 1,500

(B) Rs 1,000

(C) Rs. 500

(D) Rs. 2,000



13. Which one of the following expresses error in computer data?



(A) chip

(B) byte

(C) bug

(D) bit



14.Assertion (A) Graphite is a good lubricant. Reason (R) Graphite is good conductor of electricity. Select the correct answer from the codes given below Codes:



(A) Both (A) and (R) are true and (A) is the correct explanation of (A)

(B) Both (A) and (A) are true but (H) is not the correct explanation of (A)

(C) (A) is true but (R) is false

(D) (A) is false but (A) is true



15. Acid rain is caused by pollution ot environment by?



(A) Carbon dioxide and Nitrogen

(B) Carbon monoxide and Carbon dioxide

(C) Ozone and Carbon dioxide

(D) Nitrous oxide and Sulphur dioxide





16. The professional printed circuit board generally use the following as the raw material:



1.Paper base bakelite copper clad sheet

2. Glass epoxy copper clad sheet

3.Tin plated Nylon sheet

4. Silver plated pyrex sheet



17. Many switch contacts use silver as the material because



1. It is a good electrical conductor with low contact resistance

2. Silver does not tarnish

3. It is easily shaped as per requirement

4. It is very hard and does not wear off





18. A resistance of approximate value 85W is to be measured by using an ammeter of range 0-1 A having a resistance of 20 W and voltmeter of range 0-50V having a resistance of 5000W. Two arrangement for the measurement are shown in the figure below. Which method would you recommend?



1. Method X

2. Method Y

3. Either X or Y

4. Neither X nor Y





19. The value of capacitance across points A & B in the circuit shown below is (in microfarads)



a. .3 b. 1 c. 0.67 d. 0.33



20. It is proposed to fabricate a simple Ohm meter for measuring resistor values. A milliammeter with an internal resistance of 50 W is available. Choosing a configuration using a 3 V battery, a large resistance and the ammeter in a loop, the unknown resistor is proposed to be measured by noting the current initially and then connecting the unknown resistor across the ammeter. If the ratio of the two current is 2, what is the value of the unknown resistor (rn W ) ?



a. 3000 b. 150 c. 100 d. 50



21.The current I flowing into the branch indicated by an arrow in the circuit shown is equal to





a. 2 Amp b. 0.5 Amp c. 1 Amp d. 0.25 Amp



22. For the circuit shown, the maximum power is delivered to the load resistance RL when the value of Rg is



a. 2 ohms b. zero c. 10 ohms d. infinity



23. A signal generator is available in the laboratory, which is in good condition except for the attenuator dial which has got displaced. In order to calibrate this, a high frequency oscilloscope is available. At a particular setting of the knob an open circuit voltage of 450 mV rms is measured. If the impedance of the generator is 50 ohms, the setting of the attenuator dial is to be adjusted for



a. 6 dBm b. 1 dBm c. 0 dBm d. 10 dBm



24. The relation Loge (X + Loge (1 + X) = 0 also means that



1. X2 + X + 1 = 0



2. X2 + X - 1 = 0



3. X2 + X + e = 0



4. X2 + X – e = 0



25. The Laplace transform of the function f(t) = cos wt is



1. w/(s2 + w2)



2. s2/(s2 - w2)



3. w2/(s2 + w2)



4. s/(s2 + w2)



26. If a = b = c, one value of X which satisfies the equation



=0 is given by



a. x=a b. x=b c. x=c d. x=0



27. An LC oscillator is being analysed. If the LC tank circuit (with quality factor = Q) is isolated from the amplifying device, the impedance at the resonant frequency as measured looking into the amplifier will be



1. Q r [LC]1/2



2. ½ rp r [LC]1/2



3. – Q r[LC]1/2



4. Q r [LC]1/2





28. A battery eliminator is required to be constructed and an assortment of rectifiers, resistors and capacitors is available. However, the step down transformer available has no center tap. The following configurations for the rectifier are feasible. The one giving the lowest ripple will be



1. Full wave rectifier

2. Half wave rectified

3. Bridge rectifier

4. None



29. Chokes used in rectifier filter circuits are wound on a core with a small air gap. This is done in order to



1. Get as high an inductance as possible

2. Prevent saturation of the core

3. Absorb the ripple effectively

4. Prevent loading the transformer



30. An integrated circuit linear regulator is used at the output of a power supply having a ripple of 1 V rms. Assuming that the IC represents a typical design generally available, the output rms ripple to be expected will be



a.. 0.1 V rms b. 0.1 mV c. 100 mV d. 1.0 V rms

Here are the details of 2011 BEL Placement Paper - II job in Bharat Electronics Limited - BEL







1. Which one of the following is called the ‘metal of future’?



(A) Copper

(B) Iron

(C) Titanium

(D) Aluminum



2. The earliest coins of India were made of ?



(A) Copper

(B) Gold

(C) Lead

(D) Silver



3. The Mongols appeared for the first time on the banks of Indus during the reign of?



(A) Balban

(B) Iltutrnish

(C) Qutubuddin Aibak

(D) Razia



4. The first woman ruler of medieval India was?



(A) Chand Bibi

(B) Durgavati

(C) Noorjahan

(D) Razia



5. The Moplah Rebellion (1921) took place in?



(A) Malabar

(B) Marathawada

(C) Telengana

(D) Vidarbha



6. Which part of the Constitutions of India has been described as the: Soul of the Constitution ?



(A) Directive principles of State policy

(B) Fundamental rights

(C) Preamble

(D) Right to constitutional remedies



7. The first state to implement the Panchayati Raj System in India was?



(A) Uttar Pradesh

(B) Rajasthan

(C) Gujarat

(D) Karnataka



8. Who has the right to seek advisory opinion of the Supreme Court on any question of law?



(A) Prime Minister

(B) President

(C) Any High Court

(D) All of the above



9. Consider the following statements about the Governor of a State



1. He is appointed by the President.

2. He holds office at the pleasure of the President.

3. The executive power of the: State vests in him.

4. Normally he holds office for five years.

Select the correct answer from the codes given below

(A) l and 2

(B) 1,2 and 3

(C) 1,2 and 4

(D) All the four



10. Which one of the following pairs is not correctly matched ?



(A) Ahmedabad—Sabarmati

(B) Lucknow —Gomti

(C) Bhubaneshwar—Mahanadi

(D) Ujjain-Shipra



11. Dilwara Jain temple is situated at?



(A) Palitana

(B) Mount Abu

(C) Sonagiri

(D) Girinarji



12. Which one of the following is the biggest shipping canal in the world?



(A) Kiel Canal

(B) Panama Canal

(C) Soo Canal

(D) Suez Canal



13. Where was the battle of Plassey fought?



(A) Karnal

(B) Haldighati

(C) Mysore

(D) Bengal



14. Who was the first Vice-President of India?



(A) Dr. S. Radhakrishnan

(B) Dr. Rajendra Prasad

(C) C. V. Raman

(D) Jawahar Lal Nehru



15. What was the reason behind the mutiny of 1857?



(A) Cartridge containing fat

(B) Frustration in soldiers

(C) Failure of British Government

(D) Administrative research



16. For VHF interfering waves generated by automobile ignition systems or other electrical equipment located close to the ground, specify which of the following components of the interfering signal are significant at receiving locations such as used in the reception of TV signals:



1.Horizontal polarization component

2.Vertical polarization component

3. Both horizontal and vertical polarization components

4. Neither horizontal nor vertical polarization components



17. The ratio of lower frequency limit to the MUF for radio communication at short-wave is generally



1. Smaller at night than in the day time

2. Larger at night than in the day time

3. Same at night and in the day time

4. A maximum during the evening times



18. Two UHF amateur radio antenna placed at the same height and 30 statute miles apart are to be such that each is on the radio horizon line of the other. The height of the antennas should be



a. 56.25 ft b. 112.5ft c. 150ft d. 225ft



19. A transmitter with a radiated power of 1 KW produces a field strengthof 300 mv/m at a distance of 1 Km from the antenna. If the transmitter power is increased to 50 KW and the vertical directivity of the antenna is increased by a factor of 1.41, the field strength a the same distance from the antenna is approximately



a. 1.5 V/m b. 2.115 V/m c. 3.0 V/m d. 6.0 V/m



20. The directive gains of non-resonant and resonant wire antennas of equal length are approximately in the ratio of



a.. 4:1 b. 1.5:1 c. 1:1 d 3:1



21.A simple wire radiator produces a radiation field of intensity 100 mV/m at a distance point 25 Km away. The field produced (in mV/m) at a point 50 Km away in the same direction is



a. 25 b.50 c. 12.5 d. 100



22. Assuming the plane of polarization of the incoming wave and the plane of the receiving antenna to be the same, the effective height of the receiving antenna is proportional to



1. Radiation resistance

2. Power gain of the antenna

3. Physical area of the antenna

4. Wavelength, assuming other parameters being same



23. The function performed by the following circuits is



1. General combinational logic

2. Exclusive OR logic

3. Exclusive NOR logic

4. Digital comparator logic



24. Narrow trigger pulses are required to be generated from a square wave pluse train (pulse width = T). The linear wave shaping circuit would be an RC circuit (time constant = T) with the following features:



1. High pass with T << T

2. High pass with T >> T

3. Low pass with T >> T

4. Low pass with T << T



25. The circuit given below acts as



1. An OR gate

2. An AND gate

3. An inverter

4. A NOR gate



26. In the circuit shown below. if R = 0 and S = 1, the outputs Q and Q, will be



1. Q low, Q, high

2. Both low

3. Q high, Q, low

4. Both high



27. Schmitt trigger buffers are normally used as input buffers to digital logic circuit to achieve



1. Higher isolation

2. Higher fan-in-capability

3. Higher drive capability

4. Higher noise-immunity



28. For a reverse-biased PN junction. If the applied voltage is doubled the junction capacitance decreases by a factor of 2 ½. Assuming the junction acts as a parallel plate condenser, the average spacing between the plates changes by a factor of



1. 22 b.2 c. 1/21/2 d. 21/2



29. Many frequency sources use a piezo-electric resonator in the feedback circuit essentially to achieve a



1. Miniature product

2. Low cost design

3. Stable frequency

4. Large output power



30. A pulse train has the following characteristics:



Peak amplitude = 10 V, Pulse ON time 1 sec



Pulse OFF time = 4 sec



The pulse train is passed through a high pass RC filter with a large time constant. The amplitude of the positive peak at the output will be



1. .10 V b. 2V c. 4V d. 8V

BEL Placement Paper : BEL Technical Database Electrical and electronics 17 Sep 2012

BEL Technical Questions with answers
1. The gray code equivalent of binary 1100 is
a. 1011
b. 1101
c. 1010-Answer
d. 1100

2. A Multiplexer has
a. Multiple inputs and single output--Answer
b. Single input and Multiple outputs
c. Multiple inputs and Multiple outputs
d. Multiple inputs for Storage of Data

3. A binary half adder
a. Adds two binary digits and produces their sum and carry-Answer
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-Answer
d. Counting the no of programmes

5. An example of volatile memory is
a. RAM-Answer
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-Answer
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-Answer
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-Answer
c. 50ma
d. no change

9. The noise figure of an ideal amplifier in decibel is
a. 0.5
b. 0-Answer
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-Answer

11. MOSFET operates in
a. Depletion mode only
b. Enhancement mode only
c. Depletion and enhancement mode--Answer
d. None of these of the above

12. A device which behaves like SCRs is
a. UJT
b. Triac-Answer
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-Answer
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--Answer

15. Noise generated by a resistor is dependent on
a. Its Value
b. Its temperature
c. Both value and temp-Answer
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--Answer
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-Answer
d. On the stub

18. A half wave folded dipole has a radiation resistance of
a. 72 W
b.50W
c. 144W
d. 288W-Answer

19. Top loading is used in antennas for
a. Decrease in impedance
b. Increase in bandwidth
c. Increase in effective height-Answer
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--Answer
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-Answer

22. A wein bridge is used for measurement of
a. Resistance
b. Capacitance
c. Inductance
d. Audio frequency--Answer

23. The frame rate per second used in India TV is
a. 60
b. 50
c. 25-Answer
d. 30

24. VHF signals are propagated
a. Via the ionosphere
b. Along the ground-Answer
c. Through the troposphere
d. By reflection in ionosphere

25. The impedance of a 3 element yagi antenna is around
a. 75W
b. 300W-Answer
c. 50W
d. 100W

26. A PIN diode is microwave
a. Oscillator
b. Mixer
c. Detector
d. Switch-Answer

27. A transmission line of VSWR 2 has a reflection coefficient
a. 0.25
b. 0.5
c. 75-Answer
d. 0

28. Microwave repeaters are typically
a. 25
b. 50--Answer
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-Answer

30. Frequency in the UHF range is propagate by waves of
a. Ground
b. sky
c. Space-Answer
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-Answer

32. Strapping is used in a magnetron to
a. Prevent mode jumping--Answer
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-Answer
c. Low pass
d. Band stop

34. The signal propagation time in milliseconds for a geosynchronous satellite is
a. 540
b. 270
c. 135-Answer
d. 100

35. The silicon solar cell is a
a. Photo conductive
b. Photo emissive
c. Photo voltaic--Answer
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-Answer

37. A typical fibre-optic detector is
a. Step recovery diode
b. Light emitting diode
c. Avalanche photo diode-Answer
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-Answer
d. Suppressing noise interference

39. The most effective anti-jamming technique is
a. Frequency hopping--Answer
b. Spread Spectrum
c. Frequency synthesis
d. Burst transmission

40. Mono-mode is a term used in
a. Fibre-optics-Answer
b. Radar
c. Satellite communication
d. Magnetics

41. Monopulse technique is used in
a. Radar--Answer
b. Radio relay
c. Data communication
d. Fibre-optics

42. HDLC is a term for
a. Data communication protocol-Answer
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-Answer
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-Answer
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--Answer

46. In a monolithic IC, resistors are formed from
a. Ceramic materials
b. Copper
c. P-type semiconductor-Answer
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--Answer

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 -Answer
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 -Answer
c. Capacitive
d. None of these of these

50. The wave length of 1 Giga hertz frequency signal is
a. 10cm
b. 30cm -Answer
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]-Answer

52. Which family of the following integrated circuits has the highest speed
a. DTL
b. ECL -Answer
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-Answer
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 -Answer
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 -Answer
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 -Answer
d. None of these

57. The device used for isolating the transmitter and receiver in a radar system is called
a. Diplexer
b. Duplexer-Answer
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-Answer
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-Answer
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-Answer
b. A series resistance
c. Varying its supply voltage
d. Current through the device

61. Electron volt is equivalent to
a. 3.8 * 10-20 erg
b. 1.602 * 10-12 erg-Answer
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-Answer
c.Angle of incident of radiation
d. Surface conditions of the surface

63. Flux is expressed in radio-metric system in
a. Lumens-Answer
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-Answer
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-Answer
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-Answer

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 -Answer
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 -Answer
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-Answer

70. Microwave tube based on velocity modulation principle is
a. Klystron-Answer
b.Magnetron
c. Light house tube
d. Traveling wave tube

71. Noise output from the receiver decreases uniformly with noise side band frequency for
a. Frequency modulation-Answer
b. Amplitude modulation
c. Pulse amplitude modulation
d. None of these

72. In amplitude modulation the maximum permissible modulation index is
a. Unity -Answer
b. 100
c. infinity
d. None of these

73. In frequency modulation the maximum permissible modulation index is
a. Unity
b. 50 -Answer
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-Answer
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 -Answer
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-Answer
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-Answer
c. For low singal strength
d. For FM receiver

78. Selectivity means
a. Bandwidth-Answer
b. Gain
c. Modulation index
d. None of these

79. Narrow bandwidth broadcast reduces
a. The quality and noise-Answer
b. Quality alone
c. Noise alone
d. Quality and intelligibility

80. Squelch means keeping the receiver
a. ON in the absence of carrier
b
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 -Answer
d.All the above

82. Noise figure of an amplifier is defined as
a. Input SNR output SNR
b. Input SNR / output SNR-Answer
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 -Answer
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% -Answer
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 -Answer
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-Answer
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]-Answer
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)-Answer
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-Answer
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-Answer
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-Answer
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-Answer
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 -Answer
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-Answer
d. None of these of the above

95. Which of the following statement is true
a. Tunnel diode & IMPATT diode are negative resistance devices-Answer
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-Answer
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 -Answer
c. 16
d. 32 times

98. 900 rpm is equal to
a. 94.2 rad/sec
b. 47.1 rad/sec-Answer
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-Answer
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)--Answer

BEL Placement Paper : BEL Technical Other Solved Technical questions 17 Sep 2012

Bel sample electronics solves question paper

1. Match the following List ­ I with List ­ II
List ­ I List ­ II
1. P­Type Semiconductor a) Aluminium
2. Intrinsic Semiconductor b) Phosphorus
3. Trivalent c) Impure Semiconductor
4. Pentavalent d) Pure Semiconductor
a) 1­d, 2­a, 3­c, 4­
b) 1­c, 2­d, 3­a, 4­b -Answer
c) 1­a, 2­d, 3­b, 4­c
d) 1­b, 2­d, 3­a, 4­c

2. Hall effect used to measure
a) Electric field intensity
b) Capacitance
c) Conductivity of material -Answer
d) None of the above

3. Following truth table is correspond to

a) OR gate -Answer
b) AND gate
c) NAND gate
d) XNOR gate

4. Which one of the following gate is called as Universal gate
a) AND gate
b) XNOR gate
c) OR gate d
d) NAND gate -Answer



a) Half adder -Answer
b) Fulladder
c) Half subtractor
d) Full subtractor

6. The binary number 1010 is equivalent to the decimal number
a) 5
b) 6
c) 10 -Answer
d) 11

7. For what condition Buchholz relay gives an alarm?
a) Transformer tank below oil levels detected -Answer
b) Transformers tank above oil level detected
c) No oil detected
d) None of the above

8. The unit of conductivity is
a) Ohm­metre
b) Siemens/metre -Answer
c) Celcius
d) None of the above

9. A 50HZ 20 poles alternator will run at
a) Greatest speed
b) Smallest speed -Answer
c) Moderate speed
d) None of the above

10. A Step­up transformer used to increase
a) Frequency
b) Current
c) Voltage -Answer
d) None of the above

11. The LASCR operates like a
a) Varactor
b) Latch -Answer
c) Photo diode
d) LED

12. A negative­resistance, microwave device for oscillator application is
a) IMPATT diode
b) Step Recovery diode -Answer
c) Gunn diode
d) Schottky diode

13. The IMPATT diode operates at frequency range between
a) 10 ­ 100 -Answer
b) 20 ­ 200 GHZ
c) 5 ­ 500 GHZ
d) 2 ­ 50 GHZ

BEL Placement Paper : BEL Placement Paper Civil,Mechanical,Chemical,Computer 29 October 2012

BEL Mechanical Engineering Interview Questions

1.What is mechanical engineering?
Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the design, production, and operation of machines and tools

2.Explain mechatronics?
Mechatronics refers to the efficient and effective integration of mechanical systems and electronics. It is a blend of mechanics and electronics, and has come to mean the synergistic use of:

precision engineering
control theory
computer science
mathematics
sensor technology, to design enhanced or "smart" products, processes and systems.

3. what are Carnot cycle, Otto cycle, and Diesel cycle?
Carnot cycle - Represents most efficient cycle that operates between two fixed temperatures TH and TL
Otto Cycle - Represents ideal cycle for spark-ignition (SI) engines. Ex: Processes in 4-stroke engine cycle
Diesel cycle - Represents ideal compression ignition (CI) engine. Almost similar to Otto cycle

4.Explain simple vapour compression cycle in refrigerator?
Compression refrigeration cycles in general take advantage of the idea that highly compressed fluids at one temperature will tend to get colder when they are allowed to expand. If the pressure change is high enough, then the compressed gas will be hotter than our source of cooling (outside air, for instance) and the expanded gas will be cooler than our desired cold temperature. In this case, we can use it to cool at a low temperature and reject the heat to a high temperature.

Vapor-compression refrigeration cycles specifically have two additional advantages. First, they exploit the large thermal energy required to change a liquid to a vapor so we can remove lots of heat out of our air-conditioned space. Second, the isothermal nature of the vaporization allows extraction of heat without raising the temperature of the working fluid to the temperature of whatever is being cooled.

5.Which compression is usually used in a/c?
Hermetically sealed reciprocating compressor .

Why don,t CI engine need a spark?
The compression ratio is high enough to combust the diesel without the aid of sparkplugs

What is MPFI, TPFC system?
What are the law of thermodynamics and PMMs?
Which is your favourite car and why?
What is your favourite two-wheeler and why?
During intial start-up,exhaust smoke appears white. why?
What are the common automobile specification?
Define heat exchangers?
Define conduction, convection and radiation?
Explain concept of black body?
Describe the lubrication system in IC engines?
Can poisson,s ratio be negative?
What is bending moment equation and torque equation?
What is crippling load and its equations?
What are principal stresses and strains?
What is Endurance limit?
Draft tube and its application?
What is six sigma?
Where does the future of mechanical engineering lie?
Differentiate between absolute and kinematics viscosity?
What is magnus efect?
Compare the constrctional details of a petrol and diesel engine?
Which gear is used to obtain maximum speed ratio?

BEL General Questions for Civil Engineers

Q: According to you, what is the best design for building bridges?


Q: What are all the new civil construction materials and concepts?


Q: What is softsoil?


Q: Explain your project management?


Q: What are the CAD software versions you have used?


Q: What are some of the different ways to lay a foundation?


Q: Why is a manhole round?


Q: What is earth?

BELGeneral Questions for Mechanical Engineers

Q: Explain about power technology?


Q: How is SAP useful for mechanical engineers?


Q: What are the different types of bearings? What are different types of rivets?


Q: What is the applicability of mechanical engineering in the industry?


Q: Explain Newton’s Laws.


Q: How is a factor of safety used in design?


Q: Interpret a Stress vs. Strain Curve.


Q: What types of equations or theories would be used in Static Failure?


Q: What types of equations would be used in Fatigue Failure?


Q: Which one is more efficient– a four stroke engine or a two stroke? Why?



BEL-General Questions for Electrical Engineers

Q: Why electrical engineering?


Q: What is the difference between earthing and grounding?


Q: Why transistors are not used as switching devices?


Q: Define watt.


Q: How are analog signals converted to digital signals?


Q: Explain the differences between a transistor and capacitor.


Q: Describe the functions of a diode.


Q: Describe the basic elements of an integrated circuit.


Q: What is a UPS?


Q: Describe how energy is stored in an inductor on electronic level.


Q: What is the difference between a Verilog task and a Verilog function?


Q: What is the difference between a Vera task and a Verilog task?

BEL-General Questions for Chemical Engineers

Q: How do you go about mixing two unknown chemicals?


Q: How would you separate water and benzene?


Q: How do you calculate the sonic velocity of a gas stream?


Q: What is unit operation?


Q: What are the effects of oils on the properties of Polyolefins?

BEL General Questions for Computer Science Engineers

Q: Write a function that returns the factorial of a number.


Q: What are data structures?


Q: What are condition statements?


Q: Define exception handling with example.


Q: Name the operating systems you are familiar with.


Q: What is the difference between a bug and a virus?


Q: What is hyper threading (HT technology)?


Q: Which programming language would you choose to make accounting software and why?


Q: What is a database? How does it differ from data marts and data warehouses?


Q: Explain the projects undertaken by you.


Q: Write the code to sort an array of integers.


Q: What is the difference between recursion and iteration?


Q: What are the similarities between recursion and iteration?


Q: What are constructors?
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