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Showing posts with label Multiple Chioce Questions and Answers. Show all posts
Showing posts with label Multiple Chioce Questions and Answers. Show all posts
Tuesday, 11 October 2016
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Heating and Welding -- MCQs with Answers
Heating and Welding -- MCQs with Answers
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1. Which of the following is an advantage of heating by electricity ?
(a) Quicker operation
(b) Higher efficiency
(c) Absence of flue gases
(d) All of the above
Ans: d
2. ________ has the highest value of thermal conductivity.
(a) Copper
(b) Aluminium
(c) Brass
(d) Steel
Ans: a
3. Which of the following heating methods has maximum power factor ?
(a) Arc heating
(b) Dielectric heating
(c) Induction heating
(d) Resistance heating
Ans: d
4 method has leading power factor
(a) Resistance heating
(b) Dielectric heating
(c) Arc heating
(d) Induction heating
Ans: b
5 is used for heating non-conducting materials.
(a) Eddy current heating
(b) Arc heating
(c) Induction heating
(d) Dielectric heating
Ans: d
6. Which of the following methods of heating is not dependent on the frequency of supply ?
(a) Induction heating
(b) Dielectric heating
(c) Electric resistance heating
(d) All of the above
Ans: c
7. When a body reflects entire radiation incident on it, then it is known as
(a) white body
(b) grey body
(c) black body
(d) transparent body
Ans: a
8. For the transmission of heat from one body to another
(a) temperature of the two bodies must be different
(b) both bodies must be solids
(c) both bodies must be in contact
(d) at least one of the bodies must have some source of heating
Ans: a
9. Heat transfer by condition will not occur when
(a) bodies are kept in vacuum
(b) bodies are immersed in water
(c) bodies are exposed to thermal radiations
(d) temperatures of the two bodies are identical
Ans: d
10. A perfect black body is one that
(a) transmits all incident radiations
(b) absorbs all incident radiations
(c) reflects all incident radiations
(d) absorbs, reflects and transmits all incident radiations
Ans: b
11. Heat is transferred simultaneously by condition, convection and radiation
(a) inside boiler furnaces
(b) during melting of ice
(c) through the surface of the insulted pipe carrying steam
(d) from refrigerator coils to freezer of a refrigerator
Ans: a
12. The process of heat transfer during the reentry of satellites and missiles, at very high speeds, into earth's atmosphere is known as
(a) ablation
(b) radiation
(c) viscous dissipation
(d) irradiation
Ans: a
13. Which of the following has the highest value of thermal conductivity ?
(a) Water
(b) Steam
(c) Solid ice
(d) Melting ice
Ans: c
14. Induction heating process is based on which of the following principles ?
(a) Thermal ion release principle
(b) Nucleate heating principle
(c) Resistance heating principle
(d) Electro-magnetic induction princi¬ple
Ans: d
15. Which of the following insulating materials was suitable for low temperature applications ?
(a) Asbestos paper
(b) Diatomaceous earth
(c) 80 percent magnesia
(d) Cork
Ans: b
16. A non-dimensional number generally associated with natural convection heat transfer is
(a) Prandtl number
(b) Grashoff number
(c) Pecelet number
(d) Nusselt number
Ans: b
17. The temperature inside a furnace is usually measured by which of the following ?
(a) Optical pyrometer
(b) Mercury thermometer
(c) Alcohol thermometer
(d) Any of the above
Ans: a
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18. Which of the following will happen if the thickness of refractory wall of furnace is increased ?
(a) Heat loss through furnace wall will increase
(b) Temperature inside the furnace will fall
(c) Temperature on the outer surface of furnace walls will drop
(d) Energy consumption will increase
Ans: c
19. The material of the heating element for a furnace should have
(a) lower melting point
(b) higher temperature coefficient
(c) high specific resistance
(d) all of the above
Ans: c
20. In a resistance furnace the atmosphere is
(a) oxidising
(b) deoxidising
(c) reducing
(d) neutral
Ans: a
21. By which of the following methods the temperature inside arc nace can be varied ?
(a) By disconnecting some of the heating elements
(b) By varying the operating voltage
(c) By varying the current through heating elements
(d) By any of the above method
Ans: d
22. In induction heating ______ is abnormally high.
(a) phase angle
(b) frequency
(c) current
(d) voltage
Ans: b
23. By the use of which of the following, high frequency power supply for induction furnaces can be obtained ?
(a) Coreless transformers
(b) Current transformers
(c) Motor-generator set
(d) Multi-phase transformer
Ans: c
24. Induction furnaces are employed for which of the following ?
(a) Heat treatment of castings
(b) Heating of insulators
(c) Melting aluminium
(d) None of the above
Ans: a
25. In an electric room heat convector the method of heating used is
(a) arc heating
(b) resistance heating
(c) induction heating
(d) dielectric heating
Ans: b
26. In a domestic cake baking oven the temperature is controlled by
(a) voltage variation
(b) thermostat
(c) auto-transformer
(d) series-parallel operation
Ans: d
27. In an electric press mica is used
(a) as an insulator
(b) as a device for power factor improvement
(c) for dielectric heating
(d) for induction heating
Ans: a
28. Induction heating takes place iitwhich of the following ?
(a) Insulating materials
(b) Conducting materials which are magnetic
(c) Conducting materials which are non-magnetic
(d) Conducting materials which may or may not be magnetic
Ans: d
29. For heating element high resistivity material is chosen to
(a) reduce the length of heating element
(b) increase the life of the heating element
(c) reduce the effect of oxidation
(d) produce large amount of heat
Ans: a
30. In resistance heating highest working temperature is obtained from heating elements made of
(a) nickel copper
(b) nichrome
(c) silicon carbide
(d) silver
Ans: c
31. For intermittent work which of the following furnaces is suitable ?
(a) Indirect arc furnace
(b) Core less furnace
(c) Either of the above
(d) None of the above
Ans: a
32. Due to which of the following reasons it is desirable to have short arc length ?
(a) To achieve better heating
(b) To increase the life of roof refractory
(c) To have better stirring action
(d) To reduce problem of oxidation
(e) All of the above
Ans: e
33. In the indirect resistance heating method, maximum heat-transfer takes place by
(a) radiation
(b) convection
(c) conduction
(d) any of the above
Ans: a
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34. Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons ?
(a) To avoid initial rush of current
(b) To avoid change in kW rating with temperature
(c) Both (a) and (b)
(d) Either (a) or (b)
Ans: c
35. Which of the following methods is used to control temperature in resistance furnaces ?
(a) Variation of resistance
(b) Variation of voltage
(c) Periodical switching on and off of the supply
(d) All of the above methods
Ans: d
36. It is desirable to operate the arc furnaces at power factor of
(a) zero
(b) 0.707 lagging
(c) unity
(d) 0.707 leading
Ans: b
37. Radiations from a black body are proportional to
(a) T1
(b) T2
(c) T3
(d) T*
Ans: d
38. In arc furnace the function of choke is
(a) to stabilize the arc
(b) to imprpve, power factor
(c) to reduce severity of the surge
(d) none of the above
Ans: a
39. Ajax Wyatt furnace is started when
(a) it is filled below core level
(b) it is filled above core level
(c) it is fully empty
(d) none of the above
Ans: b
40. In electric press, mica is used because it is _______ conductor of heat but/and ________ conductor of electricity.
(a) bad, good
(b) bad, bad
(c) good, bad
(d) good, good
Ans:
41. Resistance variation method of temperature control is done by connecting resistance elements in
(a) series
(b) parallel
(c) series-parallel connections
(d) star-delta connections
(e) all of the above ways
Ans: e
42. Hysteresis loss and eddy current loss are used in
(a) induction heating of steel
(b) dielectric heating
(c) induction heating of brass
(d) resistance heating
Ans: a
43. In heating the ferromagnetic material by induction heating, heat is produced due to
(a) induced current flow through the charge
(b) hysteresis loss taking place below curie temperature
(c) due to hysteresis loss as well as eddy current loss takingplace in the charge
(d) none of the above factors
Ans: c
44. Radiant heating is used for which of the following ?
(a) Annealing of metals
(b) Melting of ferrous metals
(c) Heating of liquids in electric kettle
(d) Drying of paints and varnishes
Ans: d
45. Which of the following devices is necessarily required for automatic temperature control in a furnace ?
(a) Thermostat
(b) Thermocouple
(c) Auto-transformer
(d) Heating elements of variable resis-tance material
Ans: b
46. For radiant heating around 2250°C, the heating elements are made of
(a) copper alloy
(b) carbon
(c) tungsten alloy
(d) stainless steel alloy
Ans: c
47. Which of the following is an advantage of eddy current heating ?
(a) The amount of heat generated can be controlled accurately
(b) Heat at very high rate can be gene-rated
(c) The area of the surface over which heat is produced can be accurately controlled
(d) All of the above
Ans: d
48. The electrode of a direct arc furnace is made of
(a) tungsten
(b) graphite
(c) silver
(d) copper
Ans: b
49. Direct arc furnaces have which of the following power factors ?
(a) Unity
(b) Low, lagging
(c) Low, leading
(d) Any of the above
Ans: b
50. In direct arc furnace, which of the following has high value ?
(a) Current
(b) Voltage
(c) Power factor
(d) All of the above
Ans: a
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
Industrial Drives -- MCQs with Answers
Industrial Drives -- MCQs with Answers
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1. The selection of an electric motor for any application depends on which of the following factors ?
(a) Electrical characteristics
(b) Mechanical characteristics
(c) Size and rating of motors
(d) Cost
(e) All of the above
Ans: e
2. For a particular application the type of electric-and control gear are determined by which of the following considerations ?
(a) Starting torque
(b) Conditions of environment
(c) Limitation on starting current
(d) Speed control range and its nature
(e) All of the above
Ans: e
3. Which ofthefollowingmotors is preferred for traction work ?
(a) Universal motor
(b) D.C. series motor
(c) Synchronous motor
(d) Three-phase induction motor
Ans:
4 Which of the following motors always starts on load ?
(a) Conveyor motor
(b) Floor mill motor
(c) Fan motor
(d) All of the above
Ans: d
5 is preferred for automatic drives.
(a) Squirrel cage induction motor
(b) Synchronous motors
(c) Ward-Leonard controlled D.C. motors
(d) Any of the above
Ans: c
6. When the load is above _____ a synchronous motor is found to be more economical.
(a) 2 kW
(b) 20 kW
(c) 50 kW
(d) 100 kW
Ans: d
7. The load cycle for a motor driving a power press will be
(a) variable load
(b) continuous
(c) continuous but periodical
(d) intermittent and variable load
Ans: d
8. Light duty cranes are used in which of the following ?
(a) Power houses
(b) Pumping stations
(c) Automobile workshops
(d) All of the above
Ans: d
9. While selecting an electric motor for a floor mill, which electrical characteristics will be of least significance ?
(a) Running characteristics
(b) Starting characteristics
(c) Efficiency
(d) Braking
Ans: d
10. Which of the following motors are pre-ferred for overhead travelling cranes ?
(a) Slow speed motors
(b) Continuous duty motors
(c) Short time rated motors
(d) None of the above
Ans: c
11 is preferred for synthetic fibre mills.
(a) Synchronous motor
(b) Reluctance motor
(c) Series motor
(d) Shunt motor
Ans: b
12. Ward-Leonard controlled D.C. drives are generally used for ______ excavators.
(a) Light duty
(b) Medium duty
(c) Heavy duty
(d) All of the above
Ans: c
13. Which of the following motors is used for elevators ?
(a) Induction motor
(b) Synchronous motor
(c) Capacitor start single phase motor
(d) Any of the above
Ans: a
14. Which part of a motor needs maximum attention for maintenance ?
(a) Frame
(b) Rearing
(c) Stator winding
(d) Rotor winding
Ans: b
15 need frequent starting and stopping of electric motors,
(a) Paper mills
(b) Grinding mills
(c) Air-conditioners
(d) Lifts and hoists
Ans: d
16. Which feature, while selecting a.motor for centrifugal pump, will be of least significance ?
(a) Starting characteristics
(b) Operating speed
(c) Horse power
(d) Speed control
Ans: d
17. _______ motor is a constant speed motor.
(a) Synchronous motor
(b) Schrage motor
(c) Induction motor
(d) Universal motor
Ans: a
18. The starting torque in case of centrifugal pumps is generally
(a) less than running torque
(b) same as running torque
(c) slightly more than running torque
(d) double the running torque
Ans: a
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19. Which of the following motors are best for the rolling mills ?
(a) Single phase motors
(b) Squirrel cage induction motors
(c) Slip ring induction motors
(d) D.C. motors
Ans: d
20 is not a part of ball bearing ?
(a) Inner race
(b) Outer race
(c) Cage
(d) Bush
Ans: d
21. The starting torque of a D.C. motor is independent of which of the following?
(a) Flux
(b) Armature current
(c) Flux and armature current
(d) Speed
Ans: d
22. Rotor of a motor is usually supported on _______ bearings.
(a) ball or roller
(b) needle
(c) bush
(d) thrust
Ans: a
23. For which of the following applications D.C. motors are still preferred ?
(a) High efficiency operation
(b) Reversibility
(c) Variable speed drive
(d) High starting torque
Ans: c
24. In a paper mill where constant speed is required
(a) synchronous motors are preferred
(b) A.C. motors are preferred
(c) individual drive is preferred
(d) group drive is preferred
Ans: c
25. A reluctance motor
(a) is provided with slip rings
(b) requires starting gear
(c) has high cost
(d) is compact
Ans: d
26. The size of an excavator is usually expressed in terms of
(a) 'crowd' motion
(b) angle of swing
(c) cubic metres
(d) travel in metres
Ans: c
27. For blowers which of the following motor is preferred ?
(a) D.C. series motor
(b) D.C. shunt motor
(c) Squirrel cage induction motor
(d) Wound rotor induction motor
Ans: b
28. Belted slip ring induction motor is almost invariably used for
(a) water pumps
(b) jaw crushers
(c) centrifugal blowers
(d) none of the above
Ans: b
29. Which of the following is essentially needed while selecting a motor ?
(a) Pulley
(b) Starter
(c) Foundation pedal
(d) Bearings
Ans: b
30. Reluctance motor is a
(a) variable torque motor
(b) low torque variable speed motor
(c) self starting type synchronous motor
(d) low noise, slow speed motor
Ans: c
31 method of starting a three phase induction motor needs six terminals.
(a) Star-delta
(b) Resistance starting
(c) Auto-transformer
(d) None of the above
Ans: a
32. In ______ method of staging three phase induction motors the starting voltage is not reduced.
(a) auto-transformer
(b) star-delta
(c) slip ring
(d) any of the above
Ans: c
33. In jaw crushers a motor has to often start against ______ load.
(a) heavy
(b) medium
(c) normal
(d) low
Ans: a
34. For a motor-generator set which of the following motors will be preferred ?
(a) Synchronous motor
(b) Slip ring induction motor
(c) Pole changing induction motor
(d) Squirrel cage induction motor
Ans: a
35. Which of the following motors is usually preferred for kiln drives ?
(a) Cascade controlled A.C. motor
(b) Slip ring induction motor
(c) Three phase shunt wound com-mutator motor
(d) Any of the above
Ans: d
36. Heat control switches are used in
(a) transformers
(b) cooling ranges
(c) three phase induction motors
(d) single phase
Ans: b
37 has relatively wider range of speed control.
(a) Synchronous motor
(6) Ship ring induction motor
(c) Squirrel cage induction motor
(d) D.C. shunt motor
Ans: d
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38. In squirrel cage induction motors which of the following methods of starting cannot be used ?
(a) Resistance in rotor circuit
(b) Resistance in stator circuit
(c) Auto-transformer starting
(d) Star-delta starting
Ans: a
39. In which of the following applications the load on motor changes in cyclic order ?
(a) Electric shovels
(b) Cranes
(c) Rolling mills
(d) All of the above
Ans: d
40. Flame proof motors are used in
(a) paper mills
(b) steel mills
(c) moist atmospheres
(d) explosive atmospheres
Ans: d
41. Which of the following machines has heavy fluctuation of load ?
(a) Printing machine
(b) Punching machine
(c) Planer
(d) Lathe
Ans: b
42. For derries and winches which of the following drives can be used ?
(a) Pole changing squirrel cage motors
(b) D.C. motors with Ward-leonard con-trol
(c) A.C. slip ring motors with variable resistance
(d) Any of the above
Ans: d
43. Battery operated scooter for braking uses
(a) plugging
(b) mechanical braking
(c) regenerative braking
(d) rheostatic braking
Ans: b
44 has least range of speed control.
(a) Slip ring induction motor
(b) Synchronous motor
(c) D.C. shunt motor
(d) Schrage motor
Ans: b
45 has the least value of starting torque to full load torque ratio.
(a) D.C. shunt motor
(b) D.C. series motor
(c) Squirrel cage induction motor
(d) Slip ring induction motor
Ans: c
46. In case of _______ speed control by injecting e.m.f. in the rotor circuit is possible,
(a) d.c. shunt motor
(b) schrage motor
(c) synchronous motor
(d) slip ring induction motor
Ans: d
47. A pony motor is used for the starting which of the following motors ?
(a) Squirel cage induction motor
(b) Schrage motor
(c) Synchronous motor
(d) None of the above
Ans: c
48. In ________ the speed can be varied by changing the position of brushes.
(a) slip ring motor
(b) schrage motor
(c) induction motor
(d) repulsion motor
Ans: b
49. In which of the following applications variable speed operation is preferred ?
(a) Exhaust fan
(b) Ceiling fan
(c) Refrigerator
(d) Water pump
Ans: b
50. Heavy duty cranes are used in
(a) ore handling plants
(b) steel plants
(c) heavy engineering workshops
(d) all of the above
Ans: d
51. The travelling speed of cranes varies from
(a) 20 to 30 m/s
(b) 10 to 15 m/s
(c) 5 to 10 m/s
(d) 1 to 2.5 m/s
Ans: d
52. Besides a constant speed a synchronous rotor possesses which of the following advantages ?
(a) Lower cost
(b) Better efficiency
(c) High power factor
(d) All of the above
Ans: c
53. By the use of which of the followingm D.C. can be obtained from AC. ?
(a) Silicon diodes
(b) Mercury arc rectifier
(c) Motor generator set
(d) Any of the above
Ans: d
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
Electric Traction -- MCQs with Answers
Electric Traction -- MCQs with Answers
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1. Which of the following is an advantage of electric traction over other methods of traction ?
(a) Faster acceleration
(b) No pollution problems
(c) Better braking action
(d) All of the above
Ans: a
2. Which of the following is the voltage for single phase A.C. system ?
(a) 22 V
(b) 440 V
(c) 5 kV
(d) 15 kV
(e) None of the above
Ans: a
3. Long distance railways use which of the following ?
(a) 200 V D.C.
(b) 25 kV single phase A.C. 10.
(c) 25 kV two phase A.C.
(d) 25 kV three phase A.C.
Ans: b
4. The speed of a locomotive is controlled by
(a) flywheel
(b) gear box
(c) applying brakes 11.
(d) regulating steam flow to engine
Ans: b
5. Main traction systems used in India are, those using
(a) electric locomotives
(b) diesel engine locomotives
(c) steam engine locomotives
(d) diesel electric locomotives
(e) all of the above
Ans: e
6, in India diesel locomotives are manu¬factured at
(a) Ajmer
(b) Varanasi
(c) Bangalore
(d) Jamalpur
Ans: b
7. For diesel locomotives the range of horsepower is
(a) 50 to 200
(b) 500 to 1000
(c) 1500 to 2500
(d) 3000 to 5000
Ans: c
8. _______ locomotive has the highest operational availability.
(a) Electric
(b) Diesel
(c) Steam
Ans: a
9. The horsepower of steam locomotives is
(a) upto 1500
(b) 1500 to 2000
(c) 2000 to 3000
(d) 3000 to 4000
Ans: a
10. The overall efficiency of steam locomo¬tive is around
(a) 5 to 10 percent
(b) 15 to 20 percent
(c) 25 to 35 percent
(d) 35 to 45 percent
Ans: a
11. In tramways which of the following motors is used ?
(a) D.C. shunt motor
(b) D.C. series motor
(c) A.C. three phase motor
(d) AC. single phase capacitor start motor
Ans: b
12. In a steam locomotive electric power is provided through
(a) overhead wire
(b) battery system
(c) small turbo-generator
(d) diesel engine generator
Ans: c
13. Which of the following drives is suitable for mines where explosive gas exists ?
(a) Steam engine
(b) Diesel engine
(c) Battery locomotive
(d) Any of the above
Ans: c
14. In case of locomotives the tractive power is provided by
(a) single cylinder double acting steam engine
(b) double cylinder, single acting steam engine
(c) double cylinder, double acting steam engine
(d) single stage steam turbine
Ans: c
15. Overload capacity of diesel engines is usually restricted to
(a) 2 percent
(b) 10 percent
(c) 20 percent
(d) 40 percent
Ans: a
16. In case of steam engines the steam pressure is
(a) 1 to 4 kgf/cm2
(b) 5 to 8 kgf/cm2
(c) 10 to 15 kgf/cm2
(d) 25 to 35 kgf/cm2
Ans: c
17.. The steam engine provided on steam locomotives is
(a) single acting condensing type
(b) single acting non-condensing type
(e) double acting condensing type
(d) double acting non-condensing type
Ans: b
18. Electric locomotives in India are manufactured at
(a) Jamalpur
(b) Bangalore
(c) Chittranjan
(d) Gorakhpur
Ans: c
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19. The wheels of a train, engine as well as bogies, are slightly tapered to
(a) reduce frietion
(b) increase friction
(c) facilitate braking
(d) facilitate in taking turns
Ans: d
20. Automatic signalling is used for which of the following trains ?
(a) Mail and express trains
(b) Superfast trains
(c) Suburban and Urban electric trains
(d) All trains
Ans: b
21. The efficiency of diesel locomotives is nearly
(a) 20 to 25 percent
(b) 30 to 40 percent
(c) 45 to 55 percent
(d) 60 to 70 percent
Ans: a
22. The speed of a superfast train is
(a) 60 kmph
(b) 75 kmph
(c) 100 kmph
(d) more than 100 kmph
Ans: d
23. The number of passanger coaches that can be attached to a diesel engine locomotive on broad gauge is usually restricted to
(a) 5
(b) 10
(c) 14
(d) 17
Ans: b
24. Which of the following state capitals is not on broad gauge track ?
(a) Lucknow
(b) Bhopal
(c) Jaipur
(d) Chandigarh
Ans: c
25. Which of the following is the advantage of electric braking ?
(a) It avoids wear of track
(b) Motor continues to remain loaded during braking
(c) It is instantaneous
(d) More heat is generated during braking
Ans: a
24. Which of the following braking systems on the locomotives is costly ?
(a) Regenerative braking on electric locomotives
(b) Vacuum braking on diesel locomo-tives
(c) Vacuum braking on steam locomo-tives
(d) All braking systems are equally costly
Ans: a
27. Tractive effort is required to
(a) overcome the gravity component of train mass
(b) overcome friction, windage and curve resistance
(c) accelerate the train mass
(d) do all of the above
Ans: d
28. For given maximum axle load tractive efforts of AC. locomotive will be
(a) less than that of D.C. locomotive
(b) more than that of D.C. locomotive
(c) equal to that of D.C. locomotive
(d) none of the above
Ans: b
29. Co-efficient of adhesion reduces due to the presence of which of the following ?
(a) Sand on rails
(b) Dew on rails
(c) Oil on the rails
(d) both (b) and (c)
Ans: d
30. Due to which of the following co-efficient of adhesion improves ?
(a) Rust on the rails
(b) Dust on the rails
(c) Sand on the rails
(d) All of the above
Ans: d
31. Quadrilateral speed-time curve pertains to which of the following services ?
(a) Main line service
(b) Urban service
(c) Sub-urban service
(d) Urban and sub-urban service
Ans: d
32. Which of the following is the disadvantage of electric traction over other systems of traction ?
(a) Corrosion problems in the under-ground pipe work
(b) Short time power failure interrupts traffic for hours
(c) High capital outlay in fixed instal-lations beside route limitation
(d) Interference with communication lines
(c) All of the above
Ans: c
33. Co-efficient of adhesion is
(a) high in case of D.C. traction than in the case of AC. traction
(b) low in case of D.C. traction than in the case of AC. traction
(c) equal in both AC. and D.C. traction
(d) any of the above
Ans: b
34. Speed-time curve of main line service differs from those of urban and suburban services on following account
(a) it has longer free running period
(b) it has longer coasting period
(c) accelerating and braking periods are comparatively smaller
(d) all of the above
Ans: d
35. The rate of acceleration on suburban orurban services is restricted by the consideration of
(a) Engine power
(b) Track curves
(c) Passenger Discomfort
(d) Track size
Ans: c
36. The specific energy consumption of a train depends on which of the following ?
(a) Acceleration and retardation
(b) Gradient
(c) Distance covered
(d) All of the above
Ans: d
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37. The friction at the track is proportional to
(a) 1/speed
(b) l/(speed)2
(c) speed
(d) none of the above
Ans: c
38. The air resistance to the movement of the train is proportional to
(a) speed
(b) (speed)
(c) (speed)
(d) 1/speed
Ans: b
39. The normal value of adhesion friction is
(a) 0.12
(b) 0.25
(c) 0.40
(d) 0.75
Ans: b
40. The pulsating torque exerted by steam locomotives causes which of the following?
(a) Jolting and skidding
(b) Hammer blow
(c) Pitching
(d) All of the above
Ans: a
41. Which of the following braking systems is used on steam locomotives ?
(a) Hydraulic system
(b) Pneumatic system
(c) Vacuum system
(d) None of the above
Ans: c
42. Vacuum is created by which of the following?
(a) Vacuum pump
(b) Ejector
(c) Any of the above
(d) None of the above
Ans: c
43. The resistance encountered by a trainin motion is on account of
(a) resistance offered by air
(b) friction at the track
(c) friction at various parts of the rolling stock
(d) all of the above
Ans: d
44. Battery operated trucks are used in
(a) steel mills
(b) power stations
(c) narrow gauge traction
(d) factories for material transportation
Ans: d
45 method can bring the locomotive to dead stop.
(a) Plugging braking
(b) Rheostatic braking
(c) Regenerative braking
(d) None of the above
Ans: a
46. The value of co-efficient of adhesion will be high when rails are
(a) greased
(b) wet
(c) sprayed with oil
(d) cleaned with sand
Ans: d
47. The voltage used for suburban trains in D.C. system is usually
(a) 12 V
(b) 24 V
(c) 220 V
(d) 600 to 750 V
Ans: d
48. For three-phase induction motors which of the following is the least efficient method of speed control ?
(a) Cascade control
(b) Pole changing
(c) Rheostatic control
(d) Combination of cascade and pole changing
Ans: c
49. Specific energy consumption becomes
(a) more on steeper gradient
(b) more with high train resistance
(c) less if distance between stops is more
(d) all of the above
Ans: d
50. In main line service as compared to urban and suburban service
(a) distance between the stops is more
(b) maximum speed reached is high
(c) acceleration and retardation rates are low
(d) all of the above
Ans: d
51. Locomotive having monomotor bogies
(a) has better coefficient of adhesion
(b) are suited both for passanger as well as freight service
(c) has better riding qualities due to the reduction of lateral forces
(d) has all above qualities
Ans: d
52. Series motor is not suited for traction duty due to which of the following account ?
(a) Less current drain on the heavy load torque
(b) Current surges after temporary switching off supply
(c) Self relieving property
(d) Commutating property at heavy load
Ans: b
53. When a bogie negotiates a curve, reduction in adhesion occurs resulting in
sliding. Thus sliding is acute when
(a) wheel base of axles is more
(b) degree of curvature is more
(c) both (a) and (b)
(d) none of the above
Ans: c
54. Energy consumption in propelling the train is required for which of the following?
(a) Work against the resistance to motion
(b) Work against gravity while moving up the gradient
(c) Acceleration
(d) All of the above
Ans: d
55. An ideal traction system should have
(a) easy speed control
(b) high starting tractive effort
(c) equipment capable of with standing large temporary loads
(d) all of the above
Ans: d
56 have maximum unbalanced forces
(a) Diesel shunters
(b) Steam locomotives
(c) Electric locomotives
(d) Diesel locomotives
Ans: b
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
Control Systems -- MCQs with Answer's
Control Systems -- MCQs with Answer's
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1. In an open loop control system
(a) Output is independent of control input
(b) Output is dependent on control input
(c) Only system parameters have effect on the control output
(d) None of the above
Ans: a
2. For open control system which of the following statements is incorrect ?
(a) Less expensive
(b) Recalibration is not required for maintaining the required quality of the output
(c) Construction is simple and maintenance easy
(d) Errors are caused by disturbances
Ans: b
3. A control system in which the control action is somehow dependent on the output is known as
(a) Closed loop system
(b) Semiclosed loop system
(c) Open system
(d) None of the above
Ans: a
4. In closed loop control system, with positive value of feedback gain the overall gain of the system will
(a) decrease
(b) increase
(c) be unaffected
(d) any of the above
Ans: a
5. Which of the following is an open loop control system ?
(a) Field controlled D.C. motor
(b) Ward leonard control
(c) Metadyne
(d) Stroboscope
Ans: a
6. Which of the following statements is not necessarily correct for open control system ?
(a) Input command is the sole factor responsible for providing the control action
(b) Presence of non-linearities causes malfunctioning
(c) Less expensive
(d) Generally free from problems of non-linearities
Ans: b
7. In open loop system
(a) the control action depends on the size of the system
(b) the control action depends on system variables
(c) the control action depends on the input signal
(d) the control action is independent of the output
Ans: d
8 has tendency to oscillate.
(a) Open loop system
(b) Closed loop system
(c) Both (a) and (b)
(d) Neither (a) nor (b)
Ans: b
9. A good control system has all the following features except
(a) good stability
(b) slow response
(c) good accuracy
(d) sufficient power handling capacity
Ans: b
10. A car is rtyining at a constant speed of 50 km/h, which of the following is the feedback element for the driver ?
(a) Clutch
(b) Eyes
(c) Needle of the speedometer
(d) Steering wheel
(e) None of the above
Ans: c
11. The initial response when tne output is not equal to input is called
(a) Transient response
(b) Error response
(c) Dynamic response
(d) Either of the above
Ans: a
12. A control system working under unknown random actions is called
(a) computer control system
(b) digital data system
(c) stochastic control system
(d) adaptive control system
Ans: c
13. An automatic toaster is a ______ loop control system.
(a) open
(b) closed
(c) partially closed
(d) any of the above
Ans: a
14. Any externally introduced signal affecting the controlled output is called a
(a) feedback
(b) stimulus
(c) signal
(d) gain control
Ans: b
15. A closed loop system is distinguished from open loop system by which of the following ?
(a) Servomechanism
(b) Feedback
(c) Output pattern
(d) Input pattern
Ans: b
16 is a part of the human temperature control system.
(a) Digestive system
(b) Perspiration system
(c) Ear
(d) Leg movement
Ans: b
17. By which of the following the control action is determined when a man walks along a path ?
(a) Brain
(b) Hands
(c) Legs
(d) Eyes
Ans: d
18 is a closed loop system.
(a) Auto-pilot for an aircraft
(6) Direct current generator
(c) Car starter
(d) Electric switch
Ans: a
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19. Which of the following devices are commonly used as error detectors in instruments ?
(a) Vernistats
(b) Microsyns
(c) Resolvers
(d) Any of the above
Ans: d
20. Which of the following should be done to make an unstable system stable ?
(a) The gain of the system should be decreased
(b) The gain of the system should be increased
(c) The number of poles to the loop transfer function should be increased
(d) The number of zeros to the loop transfer function should be increased
Ans: b
21 increases the steady state accuracy.
(a) Integrator
(b) Differentiator
(c) Phase lead compensator
(d) Phase lag compensator
Ans: a
22. A.C. servomotor resembles
(a) two phase induction motor
(b) Three phase induction motor
(c) direct current series motor
(d) universal motor
Ans: a
23. As a result of introduction of negative feedback which of the following will not decrease ?
(a) Band width
(b) Overall gain
(c) Distortion
(d) Instability
Ans: a
24. Regenerative feedback implies feedback with
(a) oscillations
(b) step input
(c) negative sign
(d) positive sign
Ans: d
25. The output of a feedback control system must be a function of
(a) reference and output
(b) reference and input
(e) input and feedback signal
(d) output and feedback signal
Ans: a
26 is an open loop control system.
(a) Ward Leonard control
(b) Field controlled D.C. motor
(c) Stroboscope
(d) Metadyne
Ans: b
27. A control system with excessive noise, is likely to suffer from
(a) saturation in amplifying stages
(b) loss of gain
(c) vibrations
(d) oscillations
Ans: a
28. Zero initial condition for a system means
(a) input reference signal is zero
(b) zero stored energy
(c) ne initial movement of moving parts
(d) system is at rest and no energy is stored in any of its components
Ans: d
29. Transfer function of a system is used to calculate which of the following ?
(a) The order of the system
(b) The time constant
(c) The output for any given input
(d) The steady state gain
Ans: c
30. The band width, in a feedback amplifier.
(a) remains unaffected
(b) decreases by the same amount as the gain increase
(c) increases by the sane saaaajajt as the gain decrease
(d) decreases by the same amount as the gain decrease
Ans: c
31. On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ?
(a) Frequency
(b) Loop gain
(c) Forward gain
(d) All of the above
Ans: d
32. The transient response, with feedback system,
(a) rises slowly
(b) rises quickly
(c) decays slowly
(d) decays quickly
Ans: d
33. The second derivative input signals modify which of the following ?
(a) The time constant of the system
(b) Damping of the system
(c) The gain of the system
(d) The time constant and suppress the oscillations
(e) None of the above
Ans: d
34. Which of the following statements is correct for any closed loop system ?
(a) All the co-efficients can have zero value
(6) All the co-efficients are always non-zero
(c) Only one of the static error co-efficients has a finite non-zero value
(d) None of the above
Ans: c
35. Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ?
(a) The system is relatively stable
(b) The system is highly stable
(c) The system is highly oscillatory
(d) None of the above
Ans: c
36. Due to which of the following reasons excessive bond width in control systems should be avoided ?
(a) It leads to slow speed of response
(b) It leads to low relative stability
(c) Noise is proportional to band width
(d) None of the above
Ans: c
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38. In an automatic control system which of the following elements is not used ?
(a) Error detector
(b) Final control element
(c) Sensor
(d) Oscillator
Ans: d
39. In a control system the output of the controller is given to
(a) final control element
(b) amplifier
(c) comparator
(d) sensor
(e) none of the above
Ans: a
40. A controller, essentially, is a
(a) sensor
(b) clipper
(c) comparator
(d) amplifier
Ans: c
41. Which of the following is the input to a controller ?
(a) Servo signal
(b) Desired variable value
(c) Error signal
(d) Sensed signal
Ans:
42. The on-off controller is a _____ system.
(a) digital
(b) linear
(c) non-linear
(d) discontinuous
Ans:
43. The capacitance, in force-current analogy, is analogous to
(a) momentum
(b) velocity
(c) displacement
(d) mass
Ans: d
44. The temperature, under thermal and electrical system analogy, is considered analogous to
(a) voltage
(b) current
(c) capacitance
(d) charge
(e) none of the above
Ans: a
45. In electrical-pneumatic system analogy the current is considered analogous to
(a) velocity
(b) pressure
(c) air flow
(d) air flow rate
Ans: d
46. In liquid level and electrical system analogy, voltage is considered analogous to
(a) head
(b) liquid flow
(c) liquid flow rate
(d) none of the above
Ans: a
47. The viscous friction co-efficient, in force-voltage analogy, is analogous to
(a) charge
(b) resistance
(c) reciprocal of inductance
(d) reciprocal of conductance
(e) none of the above
Ans: b
48. In force-voltage analogy, velocity is analogous to
(a) current
(b) charge
(c) inductance
(d) capacitance
Ans: a
49. In thermal-electrical analogy charge is considered analogous to
(a) heat flow
(b) reciprocal of heat flow
(c) reciprocal of temperature
(d) temperature
(e) none of the above
Ans: d
50. Mass, in force-voltage analogy, is analogous to
(a) charge
(b) current
(c) inductance
(d) resistance
Ans: c
51. The transient response of a system is mainly due to
(a) inertia forces
(b) internal forces
(c) stored energy
(d) friction
Ans: c
52 signal will become zero when the feedback signal and reference signs are equal.
(a) Input
(b) Actuating
(c) Feedback
(d) Reference
Ans: b
53. A signal other than the reference input that tends to affect the value of controlled variable is known as
(a) disturbance
(b) command
(c) control element
(d) reference input
Ans: a
54. The transfer function is applicable to which of the following ?
(a) Linear and time-in variant systems
(b) Linear and time-variant systems
(c) Linear systems
(d) Non-linear systems
(e) None of the above
Ans: a
55. From which of the following transfer function can be obtained ?
(a) Signal flow graph
(b) Analogous table
(c) Output-input ratio
(d) Standard block system
(e) None of the above
Ans: a
56 is the reference input minus the primary feedback.
(a) Manipulated variable
(b) Zero sequence
(c) Actuating signal
(d) Primary feedback
Ans: c
57. The term backlash is associated with
(a) servomotors
(b) induction relays
(c) gear trains
(d) any of the above
Ans:
58. With feedback _____ increases.
(a) system stability
(b) sensitivity
(c) gain
(d) effects of disturbing signals
Ans: a
59. By which of the following the system response can be tested better ?
(a) Ramp input signal
(b) Sinusoidal input signal
(c) Unit impulse input signal
(d) Exponentially decaying signal
Ans: c
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
Measurement and Instrumentation -- MCQs with Answers
Measurement and Instrumentation -- MCQs with Answers
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1. The use of _____ instruments is merely confined within laboratories as stand¬ardizing instruments.
(a) absolute
(b) indicating
(c) recording
(d) integrating
(e) none of the above
Ans: a
2. Which of the following instruments indicate the instantaneous value of the electrical quantity being measured at the time at which it is being measured ?
(a) Absolute instruments
(b) Indicating instruments
(c) Recording instruments
(d) Integrating instruments
Ans: b
3. _____ instruments are those which measure the total quantity of electricity delivered in a particular time.
(a) Absolute
(b) Indicating
(c) Recording
(d) Integrating
Ans: d
4. Which of the following are integrating instruments ?
(a) Ammeters
(b) Voltmeters
(c) Wattmeters
(d) Ampere-hour and watt-hour meters
Ans: d
5. Resistances can be measured with the help of
(a) wattmeters
(b) voltmeters
(c) ammeters
(d) ohmmeters and resistance bridges
(e) all of the above
Ans: d
6 According to application, instruments are classified as
(a) switch board
(b) portable
(c) both (a) and (b)
(d) moving coil
(e) moving iron
(f) both (d) and (e)
Ans: c
7. Which of the following essential features is possessed by an indicating instrument ?
(a) Deflecting device
(b) Controlling device
(c) Damping device
(d) All of the above
Ans: d
8. A _____ device prevents the oscillation of the moving system and enables the latter to reach its final position quickly
(a) deflecting
(b) controlling
(c) damping
(d) any of the above
Ans: c
9. The spring material used in a spring control device should have the following property.
(a) Should be non-magnetic
(b) Most be of low temperature co-efficient
(c) Should have low specific resistance
(d) Should not be subjected to fatigue
(e) All of the above
Ans: e
10. Which of the following properties a damping oil must possess ?
(a) Must be a good insulator
(b) Should be non-evaporating
(c) Should not have corrosive action upon the metal of the vane
(d) The viscosity of the oil should not change with the temperature
(e) All of the above
Ans: e
11. A moving-coil permanent-magnet instrument can be used as _____ by using a low resistance shunt.
(a) ammeter
(b) voltmeter
(c) flux-meter
(d) ballistic galvanometer
Ans: a
12. A moving-coil permanent-magnet instrument can be used as flux-meter
(a) by using a low resistance shunt
(b) by using a high series resistance
(c) by eliminating the control springs
(d) by making control springs of large moment of inertia
Ans: c
13. Which of the following devices may be used for extending the range of instruments ?
(a) Shunts
(b) Multipliers
(c) Current transformers
(d) Potential transformers
(e) All of the above
Ans: e
14. An induction meter can handle current upto
(a) 10 A
(b) 30 A
(c) 60 A
(d) 100 A
Ans: d
15. For handling greater currents induction wattmeters are used in conjunction with
(a) potential transformers
(b) current transformers
(c) power transformers
(d) either of the above
(e) none of the above
Ans: b
16. Induction type single phase energy meters measure electric energy in
(a) kW
(b) Wh
(c) kWh
(d) VAR
(e) None of the above
Ans: c
17. Most common form of A.C. meters met with in every day domestic and industrial installations are
(a) mercury motor meters
(b) commutator motor meters
(c) induction type single phase energy meters
(d) all of the above
Ans: c
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18. Which of the following meters are not used on D.C. circuits
(a) Mercury motor meters
(b) Commutator motor meters
(c) Induction meters
(d) None of the above
Ans: c
19. Which of the following is an essential part of a motor meter ?
(a) An operating torque system
(b) A braking device
(c) Revolution registering device
(d) All of the above
Ans: d
20. A potentiometer may be used for
(a) measurement of resistance
(b) measurement of current
(c) calibration of ammeter
(d) calibration of voltmeter
(e) all of the above
Ans: e
21 is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another,
(a) Tangent galvanometer
(b) Meggar
(c) Current transformer
(d) None of the above
Ans: b
22. The household energy meter is
(a) an indicating instrument
(b) a recording instrument
(c) an integrating instrument
(d) none of the above
Ans: c
23. The pointer of an indicating instrument should be
(a) very light
(b) very heavy
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
24. The chemical effect of current is used in
(a) D.C. ammeter hour meter
(b) D.C. ammeter
(c) D.C. energy meter
(d) none of the above
Ans: a
25. In majority of instruments damping is provided by
(a) fluid friction
(b) spring
(c) eddy currents
(d) all of the above
Ans: c
26. An ammeter is a
(a) secondary instrument
(b) absolute instrument
(c) recording instrument
(d) integrating instrument
Ans: a
27. In a portable instrument, the controlling torque is provided by
(a) spring
(b) gravity
(c) eddy currents
(d) all of the above
Ans: a
28. The disc of an instrument using eddy current damping should be of
(a) conducting and magnetic material
(b) non-conducting and magnetic material
(c) conducting and non-magnetic material
(d) none of the above
Ans: c
29. The switch board instruments
(a) should be mounted in vertical position
(6) should be mounted in horizontal position
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
30. The function of shunt in an ammeter is to
(a) by pass the current
(b) increase the sensitivity of the ammeter
(c) increase the resistance of ammeter
(d) none of the above
Ans: a
31. The multiplier and the meter coil in a voltmeter are in
(a) series
(b) parallel
(c) series-parallel
(d) none of the above
Ans: a
32. A moving iron instrument can be used for
(a) D.C. only
(b) A.C. only
(c) both D.C. and A.C.
Ans: c
33. The scale of a rectifier instrument is
(a) linear
(b) non-linear
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
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34. For measuring current at high frequency we should use
(a) moving iron instrument
(b) electrostatic instrument
(c) thermocouple instrument
(d) none of the above
Ans: c
35. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be
(a) almost zero
(b) low
(c) high
(d) none of the above
Ans: c
36. A dynamometer wattmeter can be used for
(a) both D.C. and A.C.
(b) D.C. only
(c) A.C. only
(d) any of the above
Ans: a
37. An induction wattmeter can be used for
(a) both D.C. and A.C.
(6) D.C. only
(c) A.C. only
(d) any of the above
Ans: b
38. The pressure coil of a wattmeter should be connected on the supply side of the current coil when
(a) load impedance is high
(b) load impedance is low
(c) supply voltage is low
(d) none of the above
Ans: a
39. In a low power factor wattmeter the pressure coil is connected
(a) to the supply side of the current coil
(b) to the load side of the current coil
(c) in any of the two meters at connection
(d) none of the above
Ans: b
40. In a low power factor wattmeter the compensating coil is connected
(a) in series with current coil
(b) in parallel with current coil
(c) in series with pressure coil
(d) in parallel with pressure coil
Ans: c
41. In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was
(a) unity
(6) 0.8 lagging
(c) 0.8 leading
(d) zero
Ans: a
42. In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be
(a) unity
(b) 0.5
(c) 0.3
(d) zero
Ans: b
43. The adjustment of position of shading bands, in an energy meter is done to provide
(a) friction compensation
(b) creep compensation
(c) braking torque
(d) none of the above
Ans: a
44. An ohmmeter is a
(a) moving iron instrument
(b) moving coil instrument
(c) dynamometer instrument
(d) none of the above
Ans: b
45. When a capacitor was connected to the terminal of ohmmeter, the pointer indicated a low resistance initially and then slowly came to infinity position. This shows that capacitor is
(a) short-circuited
(b) all right
(c) faulty
Ans: b
46. For measuring a very high resistance we should use
(a) Kelvin's double bridge
(b) Wheat stone bridge
(c) Meggar
(d) None of the above
Ans: c
47. The electrical power to a meggar is provided by
(a) battery
(b) permanent magnet D.C. generator
(c) AC. generator
(d) any of the above
Ans: b
48. In a meggar controlling torque is provided by
(a) spring
(b) gravity
(c) coil
(d) eddy current
Ans: c
49. The operating voltage of a meggar is about
(a) 6 V
(b) 12 V
(c) 40 V
(d) 100 V
Ans: d
50. Murray loop test can be used for location of
(a) ground fault on a cable
(b) short circuit fault on a cable
(c) both the ground fault and the short-circuit fault
(d) none of the above
Ans: c
51. Which of the following devices should be used for accurate measurement of low D.C. voltage ?
(a) Small range moving coil voltmeter
(b) D.C. potentiometer
(c) Small range thermocouple voltmeter
(d) None of the above
Ans: b
52. It is required to measure the true open circuit e.m.f. of a battery. The best device is
(a) D.C. voltmeter
(b) Ammeter and a known resistance
(c) D.C. potentiometer
(d) None of the above
Ans: c
53. A voltage of about 200 V can be measured
(a) directly by a D.C. potentiometer
(b) a D.C. potentiometer in conjunction with a volt ratio box
(c) a D.C. potentiometer in conjunction with a known resistance
(d) none of the above
Ans: b
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
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