ALL BITS

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

http://www.slideshare.net/madhugudimetla/savedfiles?s_title=hs-13014026&user_login=go2rkg2000

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




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



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

(Technical-Electronics-IInd)

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

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

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

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

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

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

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

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

5. The forbidden energy gap for silicon is

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

6. The forbidden energy gap for Germanium is

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

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

material

a. Antimony

b. Arsenic

c. Phosphorous

d. Any of the above

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

material

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

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

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

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

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

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

a. D Vd / D Id

b. D Id / D Vd

c. 1 / DVd

d. 1 / D Id

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

a. Capacitance and inductance

b. Inductance

c. Capacitance

13. Identify the circuit given below

a. AND gate

b. OR gate

c. Rectifier

d. NOR gate

14. Identify the circuit given below

a. AND gate

b. OR gate

c. Rectifier

d. NOR gate

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

a. 0.318Em

b. 0.418Em

c. 0.518Em

d. 0.618Em

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

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

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

the change in zener voltage is

c. 100. Vz. Tc DT

d. None of these of the above

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

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

19. Schottky Barrier diodes becomes important at

a. DC level operation

b. Low frequency operation

c. High frequency operation

d. None of these

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

a. Different peak value

b. Different DC level

c. Different polarity level

d. Different RMS level

Answers

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

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

a. Input signal without distorting the remaining portion

b. Input signal with distorting the remaining portion

c. Any of the above

d. None of these

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

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

junction is given by

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

b. 1 / K (Vt + Vr)N

c. K / (Vt + Vr)N

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

23. Ct = K / (Vt + Vr)N where Vt Knee voltage, Vr reverse voltage, K manufacturing dependent constant

and N dependent on type of junction, for alloy junction the value of N is

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


and N dependent on type of junction, for diffused junction the value of N is

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

25. In JFET, the drain current Id is given by (Idss drain source saturation current Vgs Gate source

voltage, Vp the pinch off voltage)

a. Idss[1 Vp/Vgs]

b. Idss(1 Vgs/Vp)2

c. Idss[1 Vgs/Vp)

d. Idss(1 Vgs/Vp)3/2

26. The shadow mask in colour tube is used to

a. Reduce X-Ray emission

b. Ensure each beam hits its own dots

c. Increase screen brightness

d. Provide degaussing for the screen

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

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

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

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

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

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

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

a. Mains transformer

b. Vertical output stage

c. Horizontal output stage

d. Horizontal oscillator

31. The output of vertical amplifier is

a. Direct current

b. Amplified vertical sync pulse

c. A saw tooth voltage

d. A saw tooth current

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

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

33. The active region in the common emitter configuration means

a. Both collector and emitter junction is reverse biased

b. The collector junction is forward biased and emitter junction

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

d. Both collector & emitter junction are forward biased

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

a. Both collector & emitter junction are reverse biased




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

a. 30%, 59%, 11%

b. 50%, 30%, 11%

c. 30%, 11%, 50%

d. 33.3%, 33.5%, 38.3%

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

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

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

a. 1/2 p RC

b. RC / 2

c. 2 C / p R

d. 2 p / RC

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

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

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

repetition rate

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

40. The distortion less output characteristic of a network means

a. Constant amplitude and linear phase shift over frequency

b. Linear phase shift and amplitude need not be constant

c. Any amplitude and phase

d. None of these

41. Single sideband means suppressed

a. Carrier

b. Carrier and one side band

c. One side band

d. None of these

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

and modulation frequency is fm)

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

43. Modulation index of the frequency modulation depends on

a. Amplitude & frequency of the modulation signal

b. Frequency and amplitude of carrier signal

c. Carrier frequency

d. None of these

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

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

45. Reactance tube modulator is known for

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

46. Bandwidth and rise time product is

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

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

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

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

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

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

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

50. Cut-in voltage V for silicon is approximately

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

Answers

b21. a22. c23. c24. a25. b26. b27. c28. d29. b30. c31. d32. d33. c34. d35. a36. c37. a38. d39. a40. a41.

b42. b43. a44. b45. b46. a47. a48. b49. b50.

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

a. Doubles

b. Halves

c. Triples

d. No change

52. Hall effect with reference to Metal or Semiconductor carrying a current I is placed in a

transversemagnetic field B, an electric field E is induced in

a. Parallel to B

b. Perpendicular to I

c. Perpendicular to both B & I

d. Perpendicular to B

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

a. 1.9 r 10-20 J

b. 1.6 r 10-19 J

c. 1.6 r 10-20 J

d. 1.16 r 10-19 J

54. Donar impurity is having a valency of:

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

55. Acceptor impurity is having a valency of

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

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

energy will

a. Decrease, & potential energy will increase

b. Increase & potential energy decrease

c. Be unaltered & potential energy decreases

d. Increase & potential energy increase

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

a. Antimony

b. Arsenic

c. Indium

d. Phosphorus

58. Excess electron is created by

a. Boran

b. Gallium

c. Indium

d. Arsenic

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

a. The di/dt of the anode current

b. The dv/dt turn on

c. L.di/dt of load inductance

d. None of these

60. Germanium has the valency of

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

61. Silicon has the valency of

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

62. Hole acts as a free charge carrier of polarity

a. Negative

b. Positive

c. Neutral

d. None of these

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

a. Colour sub carrier

b. Picture carrier

c. Sound carrier

d. None of these

64. Colour sub carrier reference burst is superimposed on the

a. Back porch of the each horizontal sync pulse

b. Front porch of the each horizontal sync pulse

c. Front porch of the each vertical sync pulse

d. Back porch of the each vertical sync pulse

65. The law of mass action with reference to semiconductor technology states that the product of free

negative & positive concentration is a constant and

a. Independent of amount of donor and acceptor doping

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

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

d. None of these

66. The snubber circuit used across SCR is a simple

a. R-L network

b. RLC network

c. LC network

d. RC network

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

a. Inductor is inserted in cathode circuit

b. Inductor is inserted in anode circuit

c. Capacitor is inserted in anode circuit

d. Capacitor is inserted in cathode circuit

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

a. Product of power and time

b. Product of armature current and back emf

c. Armature voltage and armature current

d. Field voltage and field current

69. Proportional Integral control

a. Reduces steady state error but reduces the forward gain

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

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

d. None of these

70. Increasing the servo bandwidth:

a. Improves signal to noise ratio

b. Improves speed response and lowers signal to noise ratio

c. Improves power output

d. None of these

Answers

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

71. Notch filter is

a. Low pass filter

b. High pass filter

c. Narrow stop band filter

d. Narrow pass band filter

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

a. Electro static

b. Electro magnetic

c. Magnetic

d. All the above

73. In a line of sight communication the maximum range R in miles between the receiver antenna and

transmitter antenna of height H in feet is approximately

a. R = 1.93 H

b. R = 1.23 H

c. R = 1.53 H

d. R = 2.03 H

74. In wavelength of the 60 MHz carrier frequency is

a. 10 metres

b. 15 metres

c. 5 metres

d. 2.5 metres

75. In standard TV receiving antenna the dipole element is

a. 0.5 of the wave length

b. 0.25 of the wave length

c. 1.5 of the wave length

d. 1.0 of the wave length

76. The characteristics of FET are similar to:

a. Triode

b. Tertode

c. Pentode

d. Diode

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

a. Shift register

b. Flip-flop

c. NAND gate

d. Amplifier

78. Operational amplifier characteristics are which of the following:

a. Infinite gain

b. Infinite input impedance

c. Output impedance is zero

d. All of the above

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

a. 90 to 100

b. 80 to 90

c. 0 to 50

d. 50 to 70

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

a. The open loop voltage gain reduced to 0.707

b. The open loop gain reduced to unity

c. Maximum voltage of a signal is without distortion

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

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

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

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

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

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

82. High speed amplifier design emphasized on

a. Extremely small bandwidth

b. Very slow response

c. Unity gain bandwidth after 10 MHz

d. None of these

83. Tuned amplifier having the frequency range between

a. 150 KHz 50 MHz

b. 100 Hz 100 KHz

c. 100 KHz 120 KHz

d. 50 MHz 100 MHz

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

a. 1/2 pLC

b. 2 pLC

c. 2 p / LC

d. LC / 2

85. The voltage follower can be obtained using operational amplifier

a. Without any feedback

b. Series parallel feedback of unity

c. Parallel feedback

d. Series feedback

86. Fidelity of the amplifier is when

a. It is a linear amplifier

b. It does not add or subtract any spectral components

c. It amplifier each component by the same amount

d. All of the above

87. What would be the output when two input sine waves of frequency 50 KHz and 100 KHz passed

through an amplifier in the medium signal

a. 50 KHz and 100 KHz

b. 100 KHz and 200 KHz

c. 50 KHz and 150 KHz

d. All of the above

88. The important application of Schmitt trigger is

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

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

c. To change the frequency of the input

d. None of these

89. Meaning of decoding is

a. Binary addition

b. Data transmission

c. Demultiplexing

d. Storage of binary information

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

a. 12

b. 100

c. Excess of 100

d. Excess of 1000

91. The circuit diagram represents which one of the following

a. Half adder

b. Full adder

c. Exor gate

d. AND gate

92. Flip flop cannot be called as

a. Bistable multivibrator

b. 1 Bit memory unit

c. latch

d. combinational circuit

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

a. To get the regulation in the output voltage

b. To filter out the ripple frequency

c. To increase the current rating

d. To convert AC into DC

94. Binary equivalent of the decimal number 145 is

a. 10010001

b. 1001011

c. 1010001

d. 1100010

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

a. NOR

b. AND

c. NAND

d. EXOR

96. Which of the following definition is true in the De Morgans theorem

a. Multiplication symbols are replaced by addition symbol

b. Addition symbols are replaced by Multiplication symbol

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

d. All of the above

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

a. 0001 0100 1001

b. 10010101

c. 10101001

d. None of these

98. Combinational circuit are mainly characterized by

a. Output depends upon the previous state & presents state

b. Output depends upon the input at that particular instant

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

d. Output does not depends upon the input at all

99. A flip flop is defined as

a. A bistable device with two complementary outputs

b. It is memory element

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

d. All of the above

100. Four bit code is called

a. Nibble

b. Byte

c. Word

d. Register

Answer:-

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

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

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


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. 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. ZY b.Y/Z c. Z/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. m12/m22

b. m1 m2

c. m12+m22

d. 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 [1+m]

b. It = Ic [1+m2]

c. It = Ic [1+m/22]

d. It = Ic1+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/(m/a)2 +(n/b)2

b. 2 [m/a]2 + [n/b]2

c. (m/a)2 + (n/b)2 /2

d. [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


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


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. 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

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. 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) AhmedabadSabarmati

(B) Lucknow Gomti

(C) BhubaneshwarMahanadi

(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

3. Low pass with T >> T

4. Low pass with T

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 . 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

TECHNICAL (100M)

ENG +APTI+REASONING (100M)

1.Ghost interference in TV is Due to?

2. which of the following frequency is not used in TV Broad cast ?

3. % of R,G,B in TV ?

4.one problem on self bias circuit?

5.four question on logic gate ?

6. hexadecimal to decimal conversion?

7.maximum &minimum voltages in TTL circuit ?

8. fanout of TTL circuit ?

9.if VSWR is 1, then |L|=?

10.for maximum power transfer theorem |ZL|=?

11.one question on capacitor filter, rectifier circuit ?

12. three questions on fourier transform ?

13. maximum efficiency achieved in class-A transformer fed power amplifier

14. one question on polar plot ?

15.one question on bode plot?

16. four questions on measurements ?

17.In DSB-SC ,demodulation quadrature null effect occurs when =?

18.which of the following is generation of SSB-SC ..........

19.formula for power of FM modulated signal ........

20.n-type semiconductor formed due to si is doped with arsenic

21. 1 byte is equal to 8-bits

22. group of 4-bits used in nibble

23. number of address lines required for 4096x12 ROM..........

24.volatile memory ..........

a) SRAM b)DRAM c)ROM

25.Tachometer is used to measure SPEED

26. the value of K for CLTF ,unconditionally stable

T.F=ks/(s+1)(s2+s+1)

27.determine the centroid for above CLTF?

28.determine the angle of asymptotes ?

29.Hays bridge is used when Q is ?

a) Q10 c) 1

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

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

junction is given by

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

b. 1 / K (Vt + Vr)N

c. K / (Vt + Vr)N

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

Answer : c


and N dependent on type of junction, for alloy junction the value of N is

a. 1/3

b. 2/3

c. 1/2

d. 1/4

Answer : c

3. The distortion less output characteristic of a network means

a. Constant amplitude and linear phase shift over frequency

b. Linear phase shift and amplitude need not be constant

c. Any amplitude and phase

d. None of these

Answer : a

4. Single sideband means suppressed

a. Carrier

b. Carrier and one side band

c. One side band

d. None of these

Answer : b

5. In an amplitude modulated signal, lower side band frequency is equal to (if the carrier frequency is fc

and modulation frequency is fm)

a. fm + fc

b. fc fm

c. fm r fc

d. fc / fm

Answer : b

6. The noise figure of a receiver is a measure of:

1. Excess noise generated

2. Bandwidth of the receiver

3. Gain of the receiver

4. Operating frequency

Answer :1

7. The ratio receiver is:

1. Direct detection type

2. Super regenerative type

3. Super heterodyne type

4. None of these

Answer : 3

8. In an amplitude modulation system, the modulation index is dependent upon:

1. Modulating frequency only

2. Carrier amplitude only

3. Modulating signal amplitude only

4. Modulating and carrier amplitudes only

Answer : 2

9. Image rejection mixer is generally used:

1. To reject the unwanted signal

2. To improve signal amplitude

3. To improve noise figure

4. To improve conversion loss

Answer : 3

10. The value of a resistor creating thermal noise is doubled. The noise power generated is therefore:

1. Halved

2. Quadrapuled

3. Doubled

4. Unchanged

Answer : 2


and N dependent on type of junction, for diffused junction the value of N is

a. 1/3

b. 2/3

c. 1/2

d. 1/4

Answer : a

12. In JFET, the drain current Id is given by (Idss drain source saturation current Vgs Gate source

voltage, Vp the pinch off voltage)

a. Idss[1 Vp/Vgs]

b. Idss(1 Vgs/Vp)2

c. Idss[1 Vgs/Vp)

d. Idss(1 Vgs/Vp)3/2

Answer : b

13. The shadow mask in colour tube is used to

a. Reduce X-Ray emission

b. Ensure each beam hits its own dots

c. Increase screen brightness

d. Provide degaussing for the screen

Answer : b

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

a. Y

b. Q

c. R

d. I

Answer : c

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

a. Ringing

b. Burst

c. Damper

d. Fly back

Answer : d

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

a. Ringing

b. Burst

c. Damper

d. Fly back

Answer : b

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

a. Mains transformer

b. Vertical output stage

c. Horizontal output stage

d. Horizontal oscillator

Answer : c

18. The output of vertical amplifier is

a. Direct current

b. Amplified vertical sync pulse

c. A saw tooth voltage

d. A saw tooth current

Answer : d

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

a. 29

b. 59

c. 69

d. 49

Answer : d

20. The active region in the common emitter configuration means

a. Both collector and emitter junction is reverse biased




Answer : c

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

a. Both collector & emitter junction are reverse biased




Answer : d

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

a. 30%, 59%, 11%

b. 50%, 30%, 11%

c. 30%, 11%, 50%

d. 33.3%, 33.5%, 38.3%

Answer : a

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

a. 0.64 H

b. 0.07 H

c. 0.04 H

d. 0.16 H

Answer : c

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

a. 1/2 p RC

b. RC / 2

c. 2 C / p R

d. 2 p / RC

Answer : a

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

a. RC

b. C/R

c. R/C

d. None of these

Answer : d

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

repetition rate

a. 1/d

b. d/T

c. T/d

d. T

Answer : a

27. Indicated the false statement:

1. HF mixer are generally noisier than HF amplifier

2. Impulse noise voltage is independent of bandwidth

3. Thermal noise is independent of the frequency at which it is measured

4. Industrial noise is usually of the impulse type

Answer : 2

28. If the carrier of a 100 percent modulated AM wave is suppressed the percentage power saving will

be:

a. 50

b. 70

c. 100

d. 66.6

Answer : d

29. A balanced modulator produces:

1. The carrier and Two side bands

2. The carrier and one side band

3. Two side bands alone

4. Carrier and a number of side bands

Answer : 3

30. The frequency deviation in FM system is proportional to:

1. Modulating frequency

2. Carrier amplitude

3. Modulating signal amplitude

4. None of these

Answer : 3

31. In FM, the total transmitted power is:

1. Dependent on modulating signal amplitude

2. Dependent on modulating frequency

3. Dependent on modulating index

4. Independent of the above

Answer : 4

32. A quarter wave line when short circuited at the far end behaves like

1. Pure inductor

2. Pure capacitor

3. Parallel tuned circuit

4. Series tuned circuit

Answer : 3

33. The stub line used to match transmission line with a given load impedance is generally

1. Another open circuited line

2. Another short circuited line

3. Quarter wave transmission line

4. Half wave transmission line

Answer : 2

34. The smith chart generally covers a distance of

1. Quarter wavelength

2. Half wavelength

3. One wavelength

4. Twice the wavelength

Answer : 2

35. The component generally used to sample a portion of the energy transmitted in a line is

1. Isolator

2. Circulator

3. Directional coupler

4. None of these

Answer : 3

36. The return loss in a transmission line is a measure of

1. Loss of the line

2. Standing wave ratio

3. Characteristic impedance of the line

4. None of these

Answer : 2

37. The antenna can be considered as

1. Matching the source and free space

2. Matching the source to the line

3. Matching the line and free space

4. None of these\

Answer : 3

38. The free space impedance is approximately equal to

1. 177 W

2. 277 W

3. 377 W

4. 50 W

Answer : 3

39. The polarization refers to

1. The physical orientation of the radiated wave

2. The directional of propagation of the wave

3. Direction perpendicular to the propagation of the wave

4. None of these

Answer : 3

40. If u & e are the permeability and permittivity respectively the characteristic impedance of the

medium is given by

a. ue

b. u/e

c. e/u

d. eu

Answer : 2

41. The power density at distance r from an isotropic radiator with transmitted power P is:

1. P/r2

2. P/2 p r2

3. P/4 p r2

4. None of these

` Answer : 3

42. The carrier in an FM system disappears for the lowest modulation index of:

a. 0.5

b. 1.0

c. 2.4

d. 3.5

Answer : c

43. The difference between phase and frequency modulation:

1. Is purely theoretical because they are the same in practice

2. Is too great to make the two systems compatible

3. Lies in the poorer audio response of phase modulation

4. Lies in the different definition of the modulation index

Answer : 4

44. The overall noise figure of two cascaded amplifiers is equal to

1. The algebraic sum of the two

2. The sum of the squares of the two

3. The square root of the product of the two

4. None of these

Answer : 4

45. The noise power output of an amplifier is equal to:

1. KTo BFG

2. KTo FG

3. KTo F/G

4. KTo / FG

Answer : 1

46. The effective noise temperature of an amplifier is equal to

1. (F + 1) To

2. FTo

3. (F 1) To

4. None of these

Answer : 3

47. The noise figure of an amplifier depends upon

1. Its bandwidth

2. Its gain

3. Its operating frequency

4. None of these

Answer : 4

48. The velocity of electromagnetic wave in a coaxial cable is

1. Equal to the velocity in free space

2. Less than the velocity in free space

3. Greater than the velocity in free space

4. None of these

Answer : 2

49. The standing wave ratio [SWR] in a transmission line:

1. Is proportional to the load impedance

2. Is dependent on the source impedance

3. Is a mis-match between the load and line

4. Is a measure of its power handling capability

Answer : 3

50. The standing wave ratio (SWR) is unity in a transmission line if

1. The load impedance is equal to the characteristic impedance of the line

2. The load impedance is twice that of the characteristic impedance

3. The load impedance is half of the characteristic impedance of the line

4. None of these

Answer : 1

51. The standing wave voltage node along a line repeats at the rate of if L is the wave length

a. L/4

b.L/2

c.L

d.2L

Answer : 2

52. FM modulation becomes equivalent to AM modulation if

1. FM index is greater than 1

2. FM index is equal to 1

3. FM index is very much less than 1

4. FM index less than or equal to 1

Answer : 3

53. S/N improvement of FM over AM, B is the FM modulation index

a. 3B2

b.B

c.2B

d.B/2

Answer : a

54. Picture transmission in TV employs

1. Suppressed carrier modulation

2. Vestigial side band

3. Single side band

4. None of these

Answer : 2

55. Sound transmission in TV employ

1. Amplitude modulation

2. Phase modulation

3. Frequency modulation

4. Pulse amplitude modulation

Answer : 3

56. One of the following is an indirect way of generating FM this is the:

1. Reactance FET modulator

2. Varacter divide modulator

3. Amstrong modulator

4. Reactance bipole transistor modulator

Answer : 3

57. The modulation index of AM wave is changed from 0 to 1. The transmitted power is

1. Un-changed

2. Halved

3. Doubled

4. Increased by 50%

Answer : 4

58. The isotropic antenna is represented by

1. Dipole antenna

2. Rhombic antenna

3. Yagi uda antenna

4. No such antenna exists in practice

Answer : 4

59. The gain of parabolic reflector antenna is proportional to

1. The diameter of the reflector

2. Square of the diameter of the reflector

3. Aperture area of the feed

4. None of these

Answer : 2

60. The parabolic reflector antenna are generally used to

1. Provide high gain

2. Provide pencil beam

3. Increase bandwidth of operation

4. None of these

Answer : 2

61. Cassegrain feed is used with a parabolic reflector to

1. Increase gain of the system

2. Increase the bandwidth of the system

3. Reduce the size of the main reflector

4. Allow the feed to be placed at a convenient point

Answer : 4

62. A helical antenna is used for satellite tracking because of its

1. Circular polarization

2. Maneuverability

3. Broad bandwidth

4. Good front to back ratio

Answer : 1

63. The discone antenna is

1. A useful direction finding antenna

2. Used as a radar receiving antenna

3. Circularly polarized like other circular antenna

4. Useful as a VHF receiving antenna

Answer : 4

64. Waveguides are used mainly for microwave signals because

1. They depend on straight line propagation which applies to microwaves only

2. Losses would be too heavy at lower frequencies

3. There are no generators powerful enough to excite them at lower frequencies

4. They would be too bulky at lower frequencies

Answer : 4

65. The wavelength in a waveguide

1. Is greater than in free space

2. Depends only on the waveguide dimensions and the free-space wavelength

3. Less than the free space wavelength

4. Equal to the free space wavelength

Answer : 1

66. The dominant mode of propagation is preferres with rectangular waveguide because(indicate false

statement)

1. It leads to the smallest waveguide dimensions

2. The resulting impedance can be matched directly to coaxial lines

3. It is easier to excite than the other modes

4. Propagation of it without any spurious generation can be ensured

Answer : 2

67. The velocity of propagation (group velocity) in a waveguide is

1. Less than the free space velocity

2. Greater than the free space velocity

3. Equal to be free space velocity

4. None of these

Answer : 1

68. A wave can propagate in a waveguide if its cut off wavelength is

1. Greater than the free space wavelength

2. Less than the free space wavelength

3. Equal to be free space wavelength

4. None of these

Answer :3

69. The dominant mode in a rectangular waveguide is

a. TE11

b. TE10

c.TE20

d.TM11

Answer : 2

70. The characteristic wave impedance of a waveguide

1. Depends on the mode of propagation

2. Does not depend on the mode of propagation

3. Is same as the free space impedance

4. None of these

Answer : 1

71. A choke flange may be used to couple two waveguides

1. To help in the alignment of the waveguides

2. Because it is simpler than any other joint

3. To compensate the discontinuities at the joint

4. To increase the bandwidth of the system

Answer : 2

72. Frequencies in the UHF range is normally propagated by means of

1. Ground waves

2. Sky waves

3. Surface waves

4. Space waves

Answer : 4

73. As electromagnetic waves travel in free space, only one of the following can happen to them

1. Absorption

2. Attenuation

3. Reflection

4. Refraction

Answer : 2

74. High frequency wa

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