HAL

HAL
Technical-(ECE)-70 qs
1. Gate characteristic of a thyristor-

A.  is a straight line passing through origin
B.  is of the type Vg = a + bIg
C.  is a curve between Vg and Ig
D.  has a spread between two curves of Vg ? Ig

2. Which of the following memories uses a MOSFET and a capacitor as its memory cell?

A.  SRAM
B.  DRAM
C.  ROM
D.  DROM

3. In a amplitude modulated wave, the value of Vmax is 10V and Vmin is 5V. The % modulation in this case is:
A. 2%
B. 33.3%
C. 50%
D. 100%

4. When electromagnetic waves are propagated in a waveguide
A. They travel along the broader walls of the waveguide
B. They travel through the dielectric without touching the wall
C. They are reflected from the walls but they do not travel along them
D. None of these

5. An aerial is fed from an amplitude modulation amplifier. Both the modulating voltage and modulated voltage are sinusoidal. The aerial current (rms) before modulation is 5 A and it increases to 5.8A after modulation. The percentage of modulation index will be
A. 88%
B. 80%
C. 81.21%
D. 83.14%

6. The temperature coefficient of resistance of a resistor is
A. Negative
B. Positive
C. Zero
D. Infinity

7. 19. To prevent loading of the circuit under test, the input impedance of the oscilloscope
A. Be low
B. Be high
C. Capacitive
D. Inductive

8. 20. If the retrace is visible on the CRT display, then the trouble may be that
A. The fly back time of the time base saw tooth wave is not zero
B. The blanking control is not set properly
D. There is loss of SYNC signal

9. In FM, the total transmitted power is:
A. Dependent on modulating signal amplitude
B. Dependent on modulating frequency
C. Dependent on modulating index
D. Independent of the above

10. The difference between phase and frequency modulation:
A. Is purely theoretical because they are the same in practice
B. Is too great to make the two systems compatible
C. Lies in the poorer audio response of phase modulation
D. Lies in the different definition of the modulation index

11. The effective noise temperature of an amplifier is equal to
A. (F + 1) To
B. FTo
C. (F – 1) To
D. None of these

12. High frequency waves are
A. Absorbed by the F2 layer
B. Reflected by the D layer
C. Affected by the solar cycle
D. Capable of use for long distance communications on the moon

13. FM modulation becomes equivalent to AM modulation if
A. FM index is greater than 1
B. FM index is equal to 1
C. FM index is very much less than 1
D. FM index less than or equal to 1

14. Microwave links are generally preferred to coaxial for television transmission because
A. They have less overall phase distortion
B. They are cheaper
C. Of their greater bandwidths
D. Of their relative immunity to impulse noise

15. The bandwidth of a radar receiver is inversely proportional to the
A. Pulse width
B. Pulse repetition frequency
C. Pulse interval
D. Square root of the peak transmitted power

16. he Doppler effect is used in (indicate the false statement)
A. Moving target plotting on the PPI
B. MTI system
C. FM Radar
D. CW Radar

17. The A-scope displays
A. Target position and range
B. Target range but not position
C. Target position but not range
D. Neither range nor position but only velocity

18. In a TV receiver the colour killer:
A. Cuts off the chromastages during monochrome reception
B. Ensures that no colour is transmitted to monochrome receivers
C. Prevents colour overloading
D. Makes sure that the colour burst is not mistaken for sync pulses
Ans-A

19. 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
Ans-D

20. 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
Ans-D

21. 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
Ans-D

22. 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
Ans-A

23. Schottky Barrier diodes becomes important at
A. DC level operation
B. Low frequency operation
C. High frequency operation
D. None of these
Ans-A

24. 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
Ans-C

25. The saturation region in the common emitter configuration means that
A. Both collector & emitter junction are reverse biased
B. The collector junction is forward biased and emitter junction
C. The collector junction is reverse biased and emitter junction is forwared biased
D. Both collector & emitter junction are forward biased
Ans-B

26. 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%
Ans-D

27. 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
Ans-A

28. Hole is created in a semiconductor material if one of following impurities are added
A. Antimony
B. Arsenic
C. Indium
D. Phosphorus
Ans-A

29. The snubber circuit used across SCR is a simple
A. R-L network
B. RLC network
C. LC network
D. RC network
Ans-C

30. Notch filter is
A. Low pass filter
B. High pass filter
C. Narrow stop band filter
D. Narrow pass band filter
Ans-D

31. In a line of sight communication the maximum range R in miles between the receiver antenna and transmitter antenna of height H in feet is approximately
A. R = 1.93 ÖH
B. R = 1.23 ÖH
C. R = 1.53 ÖH
D. R = 2.03 ÖH
Ans-C

32. The temperature coefficient of an intrinsic semiconductor is
A. Positive
B. Negative
C. Zero
D. Like metals
Ans-B

33. 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
C. 50ma
D. no change
Ans-B

34. MOSFET operates in
A. Depletion mode only
B. Enhancement mode only
C. Depletion and enhancement mode
D. None of these of the above
Ans-C

35. Noise generated by a resistor is dependent on
A. Its Value
B. Its temperature
C. Both value and temp
D. None of these
Ans-C

36. Top loading is used in antennas for
A. Decrease in impedance
B. Increase in bandwidth
C. Increase in effective height
D. Decease the height
Ans-C

37. A PIN diode is microwave
A. Oscillator
B. Mixer
C. Detector
D. Switch
Ans-D

38. The signal propagation time in milliseconds for a geosynchronous satellite is
A. 540
B. 270
C. 135
D. 100
Ans-C

39. The silicon solar cell is a
A. Photo conductive
B. Photo emissive
C. Photo voltaic
D. Photo resistive
Ans-C

40. A gateway
A. Is a place where radars are connected
B. Permits dissimilar networks to communicate
C. Bifurcates the RF path of a transmitter
D. Is a feeder cable
Ans-B

41. 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
Ans-B

42. The operational amplifier used in analog computers have usually open loop flat gain approximately
upto
A. 1MHz
B. 100MHz
C. 10MHz
D. 0.1MHz
Ans-D

43. 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
Ans-A

44. In IMPATT diode, the voltage and current are
A. In phase
B. Out off phase by 90o
C. Out off phase by 180o
D. None of these of the above
Ans-C

45. 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
Ans-A

46. A register in the microprocessor that keeps track of the answer or results of any arithmetic or logic operation is the:
A. stack pointer
B. program counter
C. instruction pointer
D. accumulator
Ans-D

47. Which of the following are the three basic sections of a microprocessor unit?
A. operand, register, and arithmetic/logic unit (ALU)
B. control and timing, register, and arithmetic/logic unit (ALU)
C. control and timing, register, and memory
D. arithmetic/logic unit (ALU),memory, and input/output
Ans-B

48. Which of the following frequencies is associated with the 565 frequency-shift keyed decoder?
A. 1070 Hz  
B. 1270 Hz  
C. Both 1070 Hz and 1270 Hz
D. None of the above
Ans-C

49. Which of the following is not a linear/digital IC?
A. Phase-locked loop   
B. Voltage-controlled oscillator
C. Passive filter 
D. Comparator
Ans-C

50. Which of the following commands will copy the contents of location 4H to the accumulatorin a microcontroller?
A. MOV A, 04H  
B. MOV A, L4  
C. MOV L4, A
D. MOV 04H, A
Ans-A

51. How will you send and receive data to a micro-processor? (One method is I/O mapped I/O which is the other one?)

52. A logic probe is placed on the output of a gate and the display indicator is dim. A logic pulser is used on each of the input terminals, but the output indication does not change. What is wrong?
A. The dim indication on the logic probe indicates that the supply voltage is probably  low.
B. The output of the gate appears to be open.
C. The LOW indication is the result of a bad ground connection on the logic probe.
D. The gate is a tri-state device.
Ans-B

53. What is time response of a system?

54. Does the radar range depend upon the frequency of the signal transmitted?

55. The time needed for a pulse to increase from 10% to 90% of its amplitude defines:
A. pulse width   
B. propagation delay  
C. rise time
D. duty cycle
Ans-C

56. What is ALE? Explain the functions of ALE in 8085.

57. Give the bit positions reserved for the flags?

58. Write instructions to load the hexadecimal numbers 65H in register C, and 92h in the accumulator A .Display the number 65H at PORT0 and 92H at PORT1?

59. Why is data bus bi-directional?

60. What is vectored and non vectored interrupts?

61. The coefficient of coupling between two coils is 0.45. The first coil has an inductance of 75 mH and the second coil has an inductance of 105 mH. What is the mutual inductance between the coils?
A.  3.54 mH
B.  7.88 mH
C.  39.9 mH
D.  189.3 mH
Ans-C

62. The content of a simple programmable logic device (PLD) consists of:
A.  fuse-link arrays
B.  thousands of basic logic gates
C.  advanced sequential logic functions
D.  thousands of basic logic gates and advanced sequential logic functions
Ans-D

63. What causes the piezoelectric effect?
A.  heat or dissimilar metals
B.  pressure on a crystal
C.  water running on iron
D.  a magnetic field
Ans-B

64. A TRIAC:
A.  can trigger only on positive gate voltages
B.  can trigger only on negative gate voltages
C.  cannot be triggered with gate voltages
D.  can be triggered by either a positive or a negative gate voltage
Ans-D

65. Which electromagnetic device contains an armature?
A.  A speaker
B.  A dc generator
C.  A relay
D.  A solenoid
Ans-C

66. The polarity of induced voltage while a field is collapsing is
A.  independent of the force creating the field
B.  opposite to the force creating the field
C.  identical to the force creating the field
D.  present only if the force is stationary
Ans-B

67. Which statement BEST describes the operation of a negative-edge-triggered D flip-flop?
A.  The logic level at the D input is transferred to Q on NGT of CLK.
B.  The Q output is ALWAYS identical to the CLK input if the D input is HIGH.
C.  The Q output is ALWAYS identical to the D input when CLK = PGT.
D.  The Q output is ALWAYS identical to the D input.
Ans-A

68. How many flip-flops are in the 7475 IC?
A.  1
B.  2
C.  4
D.  8
Ans-C

69. Internally, a computer's binary data are almost always transmitted on parallel channels, commonly referred to as the:
A.  parallel bus
B.  serial bus
C.  data bus
D.  memory bus
Ans-C

70. The hexadecimal number 4B16 is transmitted as an 8-bit word in parallel. What is the time required for this transmission if the clock frequency is 2.25 MHz?
A.  444 ns
B.  444µ s
C.  3.55 µs
D.  3.55 ms
Ans-A

General Knowledge

1. Tripitakas are sacred books of
A. Buddhists 
B. Hindus
C. Jains 
D. None of the above
Ans-A

2. Who is the author of the book 'Nineteen Eighty Four'?
A. Thomas Hardy 
B. Emile Zola
C. George Orwell 
D. Walter Scott
Ans-C

3. The centenary of Mahatma Gandhi's arrival in South Africa was celebrated in
A. September 1993 
B. July 1993
C. August 1993 
D. May 1993
Ans-D

4. Name the Indian Chess player who has broken the World Record by finishing the game in first twelve moves?
A. Vishwanathan Anand
B  Champa Bose
C. Sakunthala Devi
D. Praveen Thipsey
Ans-A

5. The absorption of ink by blotting paper involves
A. viscosity of ink
B. capillary action phenomenon
C. diffusion of ink through the blotting
D. siphon action
Ans-B

6. Who was the first Indian to reach the semi final in Wimbledon Tennis Championship?
A.  Ramanathan Krishnan
B.  Ramesh Krishnan
C.  Laender Paes
D.  Mahesh Bhupati
Ans-A

7. What was the active medium used in the first working laser ever constructed?
A.  A diamond block
B.  Helium-neon gas
C.  A ruby rod
D.  Carbon dioxide gas
Ans-C

8. Who co-created the UNIX operating system in 1969 with Dennis Ritchie?
A.  Bjarne Stroustrup
B.  Steve Wozniak
C.  Ken Thompson
D.  Niklaus Wirth
Ans-C

9. In which decade was the ARRL founded?
A.  1940s
B.  1930s
C.  1920s
D.  1910s
Ans-D

10. How many bits is a byte?
A.  4
B.  8
C.  16
D.  32
Ans-B

11. Pollination is best defined as
A.  transfer of pollen from anther to stigma
B.  germination of pollen grains
C.  growth of pollen tube in ovule
D.  visiting flowers by insects
Ans-A

12. he centenary of Mahatma Gandhi's arrival in South Africa was celebrated in
A.  May 1993
B.  August 1993
C.  July 1993
D.  September 1993
Ans-A

13. World Literacy Day is observed on
A.  Sep 5
B.  Aug 6
C.  Sep 8
D.  Oct 24
Ans-C

14. 1981 was the international year of the
A.  Disabled
B.  Women
C.  Children
D.  Blind
Ans-A

15. Permanent Secretariat to coordinate the implementation of SAARC programme is located at
A.  Dhaka
B.  New Delhi
C.  Colombo
D.  Kathmandu
Ans-D

16. Which company manufacturers low and high power communication equipment like radius for the use of defence services and paramilitary organisations?
A.  Bharat Electronics Limited (BEL)
B.  God Shipyard Limited (GSL)
C.  Bharat Dynamic Limited (BDL)
D.  None of the above
Ans-A

17. Which atomic reactor is used for studies of uranium heavy water lattice?
A.  Apsara
B.  Zerlina
C.  Dhruva
D.  Purnima-I
Ans-B

18. Who is known as 'Indian Bismarck'?
A.  Kamaraj
B.  Sardar Vallabhbhai Patel
C.  Nehru
D.  Rajaji
Ans-B

19. Who is known as 'Desert Fox'?
A.  Bismarck
B.  Eisenhower
C.  Gen. Rommel
D.  Walter Scott
Ans-C

20. Who is the creator of the Rock Garden in Chandigarh?
A.  Pupal Jayakar
B.  Le Corbousier
C.  Glen
D.  Nek Chand
Ans-D

21. The hazards of radiation belts include
A.  deterioration of electronic circuits
B.  damage of solar cells of spacecraft
C.  adverse effect on living organisms
D.  All of the above
Ans-D

22. The humidity of the air depends upon
A.  temperature
B.  location
C.  weather
D.  All of the above
Ans-D

23. he largest fish exporting region in the world is
A.  the north-east atlantic region
B.  the north-east pacific region
C.  the north-west pacific region
D.  the south-east asian region
Ans-A

24. The longest ship canal in the world is the
A.  St. Laurence Seaway (USA and Canada)
B.  Suez canal, Egypt
C.  Kiel canal, Germany
D.  Panama canal, Central America
Ans-A

25. The most important force that provide resistance to particles towards entertainment is
A.  frictional resistance
B.  particle cohesive bonds
C.  particle adhesive bonds
D.  momentum
Ans-A
26. The most explosive type of volcano is
A.  a cinder cone
B.  the caldera
C.  basalt plateau
D.  shield volcanoes
Ans-B

27. he river Sutlej, on which the Bhakra Dam has been built, originates from
A.  a spring in Vering
B.  near Bara Lacha Pass in Lahul
C.  Rakas lake in Tibet
D.  Mansarovar lake
Ans-C

28. he radiation belts are zones in space around the
A.  Earth
B.  Jupiter and Saturn
C.  Mercury
D.  Earth, Jupiter and Saturn
Ans-D

29. The tertiary winds on the north of the Alps (Europe) are called
A.  the Chinook
B.  the foehn
C.  the sirocco
D.  the loo
Ans-B

30. G-7 includes
A.  South Africa
B.  Australia
C.  India
D.  Italy
Ans-D