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30th July 2014, 01:20 PM
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Join Date: Apr 2013
Re: Past year question papers of Probationary engineer of BEL company\

As you want to get the past year question papers of Probationary engineer of BEL company so here it is for you:

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 is1. 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
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. Minimum3. 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
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
31. Germanium transistor is preferred over silicon transistor in the following application1. 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
41. Intermediate frequency in television receiver is
1. 26-46 MHz
2. 1.6-2.3 MHz3. 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


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