D.C. Generators - Electrical engineering multiple choice questions and answers for competitive exams

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 lamina-tions 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: d

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
(c) insulation pads
(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

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