DC Generator MCQ

51. The bearings used to support the rotor shafts are generally

  1. ball bearings
  2. bush bearings
  3. magnetic bearings
  4. needle bearings

Answer. a

52. Laminations of core are generally made of

  1. cast iron
  2. carbon
  3. silicon steel
  4. stainless steel

Answer. c

53. In a commutator

  1. copper is harder than mica
  2. mica and copper are equally hard
  3. mica is harder than copper
  4. none of the above

Answer. c

54. The armature of the DC generator is laminated to

  1. reduce the frictional loss
  2. provide the bulk
  3. insulate the core
  4. reduce eddy current loss

Answer. d

55. The resistance of the armature winding depends on

  1. length of conductor
  2. the cross-sectional area of the conductor
  3. number of conductors
  4. all of the above

Answer. d

56. The commutator segments are connected to the armature conductors by means of

  1. copper lugs
  2. resistance wires
  3. insulation pads
  4. brazing

Answer. a

57. Fleming’s right-hand rule regarding the direction of induced e.m.f. correlates

  1. magnetic flux, direction of current flow and resultant force
  2. magnetic flux, direction of motion and the direction of e.m.f. induced
  3. magnetic field strength, induced voltage and current
  4. magnetic flux, direction of force and direction of motion of conductor

Answer. b

58. In DC generators the pole shoes are fastened to the pole core by

  1. rivets
  2. counter sunk screws
  3. brazing
  4. welding

Answer. b

59. For a DC generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f.?

  1. Lap winding
  2. Wave winding
  3. Either of (a) and (b) above
  4. Depends on other features of design

Answer. b

60. According to Fleming’s right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of

  1. motion of conductor
  2. lines of force
  3. either of the above
  4. none of the above

Answer. b

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