Lecturer in Electronics Engineering Polytechnics 472/2016 Answer Key

12/27/2017

Post : Lecturer in Electronics Engineering
Department : Technical Education
Category Code : 472/16
Qualification : Degree in Electronics Engineering
Date of Test : 27-12-2017

Note: Mathematics questions not included



  1. _______________ amplifier is commonly used as a frequency multiplier.
    • Class A
    • Class B
    • Class C
    • All of these

  2. Removing bypass capacitor across the emitter-leg resistor in a CE amplifier causes
    • Increase in current gain
    • Decrease in current gain
    • Increase in voltage gain
    • Decrease in voltage gain

  3. If the maximum collector current due to signal alone is 3mA, then zero signal collector current should be at least equal to
    • 6mA
    • 2mA
    • 3mA
    • 1mA

  4. In a multistage amplifier, the overall frequency response is determined by the
    • Frequency response of each stage depending on the relationships of the critical frequencies
    • Frequency response of the first amplifier
    • Frequency response of the last amplifier
    • Lower critical frequency of the first amplifier and the upper critical frequency of the final amplifier

  5. Halving the power corresponds to a ______________dB _____________
    • 10, decrease
    • 3, decrease
    • 3, increase
    • 10, increase

  6. If negative feedback is introduced in amplifiers with shunt current configuration, the input resistance will
    • Increase
    • Remains the same
    • Increase, decrease or remains the same depending on input
    • Decrease

  7. Pinch-off voltage Vp for an FET is the drain voltage at which
    • Significant drain current starts flowing
    • Drain current becomes zero
    • All free charges get removed from the channel
    • Avalanche break down takes place

  8. Compared to bipolar transistor, a JFET has
    • Higher input impedance and low voltage gain
    • Lower input impedance and high voltage gain
    • Higher input impedance and high voltage gain
    • Lower input impedance and low voltage gain

  9. Class AB operation is ______________ operation.
    • similar to class A
    • similar to class B
    • similar to class C
    • None of these

  10. The ripple factor of a full-wave rectifier circuit compared to that of a half wave rectifier circuit without filter is
    • Half of that for a half wave rectifier
    • Less than half that for a half-wave rectifier circuit
    • Equal to that of a half wave rectifier
    • None of these

  11. A capacitor is fully charged when
    • The voltage across its plates is half of the voltage from ground to one of its plates
    • The current through the capacitor is the same as when the capacitor is discharged
    • The voltage across the plates is 0.707 of the input voltage
    • The current through the capacitor is directly proportional to the area of the plates

  12. The saturation condition of transistor implies that
    • Collector current has highest possible value
    • Entire Vcc gets dropped across load resistor
    • It acts as a closed switch with negligible value of resistance
    • All of these

  13. The output of a particular Op-amp increases 8V in 12μ s. The slew rate is
    • 90 V/μ s
    • 0.67 V/μ s
    • 1.5 V/μ s
    • None of these

  14. With zero volts on both inputs, an Op-amp ideally should have an output
    • Equal to the positive supply voltage
    • Equal to the negative supply voltage
    • Equal to zero
    • Equal to CMRR

  15. Determine the output resistance of differential amplifier with three op-amp. The op-amp used in 741c, with A = 200000 and R0. The output and difference of input voltages are 44 and 11.
    • 5.5 MΩ
    • 3.5 MΩ
    • 2.4 MΩ
    • 1.5 MΩ

  16. The bandwidth of the differential amplifier increases, if the value of
    • Open Loop Voltage Gain Decreases
    • Closed Loop Voltage Gain Decreases
    • Differential Voltage Gain Decreases
    • All of these

  17. If the gain of a non-inverting averaging amplifier is one. Determine the input voltages, if the output voltage is 3v
    • V1 =6v, V1 = 3v and V1 =2v
    • V1 = 9v, V1 = 5v and V1 = -4v
    • V1 =8v, V1 = -6v and V1 = 1v
    • V1 = 7v, V1 = 4v and V1 = -3v

  18. In differential op-amp configuration a subtractor is called as
    • Scaling amplifier
    • All of the mentioned
    • Summing amplifier
    • Difference amplifier

  19. An ideal operational amplifier has
    • Infinite output impedance
    • Zero input impedance
    • Infinite bandwidth
    • All of these

  20. How the op-amp comparator should be choosen to get higher speed of operation?
    • Wider bandwidth
    • High slew rate
    • Large gain
    • None of these

  21. The gain of the first order low pass filter
    • Increases at the rate 20dB/decade
    • Increases at the rate 40 dB/decade
    • Decreases at the rate 20dB/decade
    • Decreases at the rate 40dB/decade

  22. The poles of the transfer function of normalized low pass butter worth filter exists
    • On unit circle
    • Outside unit circle
    • Inside unit circle
    • None of the mentioned

  23. A stable multivibrator operating at 150 Hz has a discharge time of 2.5 ms. The duty cycle of the circuit is
    • 50%
    • 75%
    • 95.99%
    • 37.5%

  24. Calculate the output frequency in a frequency multiplier if, fin = 200 Hz is applied to a 7 divide by N-network.
    • 1.2 kHz
    • 1.6 kHz
    • 1.4 kHz
    • 1.9 kHz

  25. Convert binary 111111110010 to hexadecimal
    • EE216
    • FF216
    • 2FE16
    • FD216

  26. Which gate is best used as a basic comparator?
    • NOR
    • OR
    • AND
    • Exclusive-OR

  27. A decoder can be used as a demultiplexer by
    • tying all enable pins LOW
    • tying all data-select lines LOW
    • tying all data-select lines HIGH
    • using the input lines for data selection and an enable line for data input

  28. A binary code that progresses such that only one bit changes between two successive codes is
    • Gray code
    • 8421 code
    • Excess-3 code
    • nine's-complement code

  29. A MOD-16 ripple counter is holding the count 10012. What will the count be after 31 clock pulses.
    • 10002
    • 10102
    • 10112
    • 11012

  30. Select the statement that best describes Read-Only Memory (ROM).
    • Non-volatile, used to store information that changes during system operation
    • Non-volatile, used to store information that does not change during system operation
    • Volatile, used to store information that changes during system operation
    • Volatile, used to store information that does not change during system operation

  31. Which of the following logic families has the shortest propagation delay?
    • CMOS
    • BiCMOS
    • ECL
    • TTL

  32. A binary input 000 is fed to a 3 bit DAC/ADC. The resultant output is 101. Find the type of error?
    • Offset error
    • Gain error
    • Settling error
    • Linearity error

  33. The transmit buffer of serial data buffer is a
    • Serial-in parallel-out register
    • Parallel-in serial-out register
    • Serial-in serial-out register
    • Parallel-in parallel-out register

  34. The register that provides control and status information about serial port is
    • IP
    • IE
    • PCON and SCON
    • TSCON

  35. The instruction that performs logical AND operation and the result of the operation is not available is
    • AAA
    • AND
    • XOR
    • TEST

  36. Which instruction cannot force the 8086 processor out of 'halt' state?
    • Hold
    • Reset
    • Interrupt request
    • Both interrupt request and reset

  37. What is the carrier frequency in an AM wave when its highest frequency component is 850 Hz and the bandwidth of the signal is 50 Hz?
    • 80 Hz
    • 695 Hz
    • 625 Hz
    • 825 Hz

  38. A 100 MHz carrier is frequency modulated by 10 KHz wave. For a frequency deviation of 50 KHz, calculate the modulation index of the FM signal.
    • 100
    • 50
    • 70
    • 90

  39. After passing the FM signal through mixer, what is the change in the frequency deviation Δ when the modulating frequency is doubled?
    • Becomes 2Δ
    • Becomes Δ/2
    • Becomes Δ2
    • Remains unchanged

  40. Pre emphasis is done
    • For boosting of modulating signal voltage
    • For modulating signals at higher frequencies
    • In FM before modulation
    • All of these

  41. What is the DFT of the four point sequence x(n) = {0, 1, 2, 3}?
    • {6, -2 + 2j-2, -2-2j}
    • {6, -2-2j, 2, -2+2j}
    • {6, -2+2j, -2, -2-2j}
    • {6, -2-2j, -2,-2+2j}

  42. Which kind of polarization is provided by helical antennas?
    • Circular
    • Elliptical
    • Plane circular
    • All of these

  43. Which has same probability of error?
    • BPSK and QPSK
    • BPSK and ASK
    • BPSK and PAM
    • BPSK and QAM

  44. In MSK, the difference between the higher and lower frequency is
    • Same as the bit rate
    • Four time the bit rate
    • Twice of the bit rate
    • Half of the bit rate

  45. The data rate of QPSK is _____________ of BPSK.
    • Thrice
    • Twice
    • Four times
    • Same

  46. TDMA allows the user to have
    • Use of same frequency channel for same time slot
    • Use of same frequency channel for different time slot
    • Use of same time slot for different frequency channel
    • Use of different time slot for different frequency channels

  47. Unauthorised access of information from a wireless device through a bluetooth connection is called``
    • Bluesnarfing
    • Bluemaking
    • Bluestring
    • None of these

  48. In a TWT the amplitude of resultant wave travelling down the helix
    • Increases exponentially
    • Increases linearly
    • Decreases exponentially
    • Is almost constant

  49. If the gate current of an SCR is increased, the forward breakdown voltage will
    • Increase
    • Decrease
    • Not be affected
    • Become infinite

  50. What is the range of the operating voltage level for LEDs?
    • 5-12 mV
    • 1.7-3.3 V
    • 5-12 V
    • 20-25 V

  51. To turn on UJT, the forward bias on the emitter diode should be ______________ the peak point voltage.
    • Less than
    • Equal to
    • More than
    • None of these

  52. The device that does not have the gate terminal is
    • Triac
    • FET
    • SCR
    • Diac

  53. If the negative potential on the control grid of CRT is increased, the intensity of spot
    • is increased
    • is decreased
    • remains the same
    • None of these

  54. The sensitivity of a multimeter is given in
    • Ω
    • amperes
    • kΩ/V
    • None of these

  55. The controlling parameter in IGBT is the
    • IG
    • VGE
    • IC
    • VCE

  56. In a loss less inverter, the average power absorbed in one period by the load must be
    • Equal to the average power supplied by the dc source
    • Greater than the average power supplied by the dc source
    • Lesser than the average power supplied by the dc source
    • Equal to the average power supplied by the ac source

  57. A module in a solar panel refers to
    • Series arrangement of solar cells
    • Parallel arrangement of solar cells
    • Series and parallel arrangement of solar cells
    • None of these

  58. A laser diode normally emits
    • Coherent and monochromatic light
    • Coherent light
    • Monochromatic light
    • Neither coherent nor monochromatic light

  59. The quality of output AC voltage of cycloconverter is improved with
    • Increase in output voltage at reduced frequency
    • Increase in output voltage at increased frequency
    • Decrease in output voltage at reduced frequency
    • Decrease in output voltage at increased frequency

  60. With the increase in the intensity of light, the resistance of a photovoltaic cell
    • Decreases
    • Increases
    • Remains same
    • None of these

  61. LED
    • is usually made from Ge
    • Uses a reverse biased junction
    • Emits light due to recombination of holes and electrons
    • Gives light output which increases with increase in temperature

  62. SPST, SPDT, DPDT and DPST are
    • Solid state relays
    • Input-output interface modules
    • Solid state switches
    • Electrical relay contact types

  63. The 8 bit micro controller has
    • Data bus of 8 bits
    • Address bus of 8 bits
    • 8K ROM
    • Both data and address bus 8 bits

  64. The additional features of 3G that are not available with 2G are//i) Mobile TV//ii) MMS//iii) Video transfers//iv) GPS
    • i, ii, iii
    • i, iii, iv
    • ii, iii, iv
    • i, ii, iii, iv

  65. 5Ah in an UPS battery specification means
    • 5A for 1 hour
    • 1A for 5 hours
    • The output power is 5 watts
    • It requires 5 hours to charge fully

  66. The 43-grade cement means that the compressive strength of the cement mortar cube after 28 days is
    • 43 GPa
    • 43 Pa
    • 43 MPa
    • None of these

  67. The process of establishing intermediate points on a survey line joining the end points is called
    • Chaining
    • Ranging
    • Pacing
    • Surveying

  68. Choice of type of foundation depends on
    • Soil type
    • Super imposed load
    • Material used
    • All these

  69. The following one is an example of electronic distance meter
    • Total station
    • Distomat
    • Electronic theodolite
    • Tacheometer

  70. The manufacturing process of concrete is in the following order
    • Proportioning, batching, mixing, transporting, placing, compacting and curing
    • Proportioning, mixing, batching, transporting, placing, compacting and curing
    • Proportioning, mixing, batching, transporting, placing, curing and compacting
    • Proportioning, transporting, mixing, batching, placing, compacting and curing

  71. In a four stroke cycle engine, the cam shaft completes
    • Half the revolution of crank shaft
    • Twice the revolutions of crank shaft
    • The same revolutions as crank shaft
    • Revolutions irrespective of crank shaft revolutions

  72. The thermal efficiency of a four stroke petrol engine as compared to two stroke petrol engine is
    • Less
    • More
    • Same for same speed
    • Same for same compression ratio

  73. While starting the engine, the pinion gear of the starter motor meshes with
    • Fly wheel ring gear
    • Gears in gear box
    • Gears in differential
    • None of these

  74. Rankine cycle consists of
    • Two isothermal processes and two constant pressure processes
    • Two isothermal processes and two constant volume processes
    • Two isentropic processes and two constant volume processes
    • Two isentropic processes and two constant pressure processes

  75. The correct order of the path of flue gas is
    • superheater, economiser, precipitator, air preheater
    • superheater, precipitator, economiser, air preheater
    • superheater, economiser, air heater, precipitator
    • superheater, air preheater, economiser, precipitator

  76. A DC source is supplying two resistors connected in parallel. If R1 = 2R2, determine the relation between the power dissipated in them
    • P1 =0.5 P2
    • P1 =P2
    • P1 =2 P2
    • P1 =4 P2

  77. If an ac voltage source of magnitude 100√2 sinwt is causing a current flow of 10 sin (wt-45) A, determine the load.
    • 10+j10Ω
    • 10-j10Ω
    • 10√2 +j10√2Ω
    • 10√2 -j10√2Ω

  78. Which one among the following is not an over voltage protective system?
    • Lightning arrester
    • Arcing horn
    • Surge arrestor
    • Earth-leakage circuit breaker

  79. If a dielectric slab of thickness 't' relative permeability of 2 is inserted between the parallel plates of an air capacitor, the capacitance of the new arrangement will
    • Not change
    • Decrease
    • Increase
    • Become zero

  80. Which one among the following is not a transmission voltage in Kerala?
    • 33 kV
    • 55 kV
    • 220 kV
    • 400 kV

  81. Who launched Kudumbasree programmes in Kerala?
    • A.B. Vajpaye
    • Man Mohan Singh
    • Rajeev Gandhi
    • Narendra Modi

  82. Which governor General of India was responsible for the appointment of Hunter Commission , the first Indian Education Commission of 3rd February 1882?
    • Lord Lytton
    • Lord Macaulay
    • Lord Rippon
    • Lord Curzon

  83. Who established "Prathyaksha Raksha Daiva Sabha" on 1909?
    • Pandit K.P. Karuppayyan
    • Poikayil Yohannan
    • Ayya Vaikunder
    • Ayyankali

  84. Which Travancore ruler proclaimed the historic temple entry proclamation on 1936?
    • Sri Moolam Thirunal Marthanda Varma
    • Uthradom Thirunal Marthanda Varma
    • Sethu Lakshmi Bai
    • Shri Chithirathirunal Balarama Varma

  85. Who was the 'Father of Malayalam Journalism'?
    • Kesari Balakrishna Pillai
    • Chengulathu Kunjirama Menon
    • Kandathil Varghese Mappila
    • T. Shiva Sankar

  86. Who is known as 'Kerala Kalidasan'?
    • Thunchathu Ezhuthachhan
    • S.K. Pottekkatt
    • Kodungalloor Kunjikuttan Thampuran
    • Kerala Varma Valiya Koil Thampuran

  87. Who was the founder and editor of the journal called 'Shreemathi'?
    • Lalithambika Antharjanam
    • Anna Chandi
    • Akkamma Cheriyan
    • Arya Pallam

  88. Who wrote the biography 'Kanneerum Kinavum'?
    • E.M.S. Namboodirippad
    • K.P. Kesava Menon
    • Kumaranasan
    • V.T. Bhattathirippad

  89. Who was famous for his quotation "The whole universe is one mind between mind and mind there is no vacuum"?
    • Sree Narayana Guru
    • Chattambi Swamikal
    • Swami Vagbhadananda
    • Ayya Vaikunder

  90. Which was the highest literacy award in Kerala?
    • Odakuzhal Award
    • Jnanpith Award
    • Vallathol Award
    • Ezhuthachan Award

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