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TOP D.C. Generators – Electrical Engineering Multiple choice Questions and Answers

1. Laminations of core are generally made of
(a)     case iron
(b)     carbon
(c) silicon steel
(d) stainless steel
Ans: c

2. Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ?
(a) 0.005 mm
(b) 0.05 mm
(c) 0.5 m
(d) 5 m
Ans: c

3. The armature of D.C. generator is laminated to
(a)     reduce the bulk
(b)     provide the bulk
(c) insulate the core
(d) reduce eddy current loss
Ans:

4. The resistance of armature winding depends on
(a)     length of conductor
(b)     cross-sectional area of the conductor
(c) number of conductors
(d) all of the above
Ans: d

5. The field coils of D.C. generator are usually made of
(a) mica
(b) copper
(c) cast iron
(d) carbon
Ans: b

6. The commutator segments are connected to the armature conductors by means of
(a) copper lugs
(b) resistance wires
(d) brazing
Ans: a

7. In a commutator
(a)     copper is harder than mica
(b)     mica and copper are equally hard
(c) mica is harder than copper
(d) none of the above
Ans: c

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8. In D.C. generators the pole shoes are fastened to the pole core by
(a) rivets
(b) counter sunk screws
(c) brazing
(d) welding
Ans: b

9. 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
(a)     motion of conductor
(b)     lines of force
(c) either of the above
(d) none of the above
Ans: b

10. Fleming’s right-hand rule regarding direction of induced e.m.f., correlates
(a) magnetic flux, direction of current flow and resultant force
(b) magnetic flux, direction of motion and the direction of e.m.f. induced
(c) magnetic field strength, induced voltage and current
(d) magnetic flux, direction of force and direction of motion of conductor
Ans: b

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