DC Generator Multiple Choice Questions and Answers

41. In D.C. generators the polarity of the interpoles

1. is the same as that of the main pole ahead
2. is the same as that of the immediately preceding pole
3. is opposite to that of the main pole ahead
4. is neutral as these poles do not play part in generating e.m.f.

42. Welding generator will have

1. lap winding
2. wave winding
3. delta winding
4. duplex wave winding

43. The number of armature parallel paths in a two-pole D.C. generator having duplex lapwinding is

1. 2
2. 4
3. 6
4. 8

44. A D.C. welding generator has

1. lap winding
2. wave moving
3. duplex winding
4. any of the above

45. The resistance of armature winding depends on

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

46. A D.C. generator works on the principle of

1. Lenzs law
2. Ohms law
3. Faradays law of electromagnetic induction
4. none of the above

47. In D.C. generators, the brushes on commutator remain in contact with conductorswhich

1. lie under south pole
2. lie under north pole
3. lie under interpolar region
4. are farthest from the poles

48. Flemings right-hand rule regarding 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

49. Compensating windings are used in D.C. generators

1. mainly to reduce the eddy currents by providing local short-circuits
2. to provide path for the circulation of cooling air
3. to neutralise the cross-magnetising effect of the armature reaction
4. none of the above

50. The field coils of D.C. generator are usually made of

1. mica
2. copper
3. cast iron
4. carbon