Top 150+ Solved DC Generators MCQ Questions Answer
Q. In a four-pole D.C. machine
a. all the four poles are north poles
b. alternate poles are north and south
c. all the four poles are south poles
d. two north poles follow two south poles
Q. Copper brushes in D.C. machine are used
a. where low voltage and high currents are involved
b. where high voltage and small cur-rents are involved
c. in both of the above cases
d. in none of the above cases
Q. A separately excited generator as compared to a self-excited generator
a. is amenable to better voltage con-trol
b. is more stable
c. has exciting current independent of load current
d. has all above features
Q. In case of D.C. machines, mechanical losses are primary function of
a. current
b. voltage
c. speed
d. none of above
Q. Iron losses in a D.C. machine are independent of variations in
a. speed
b. load
c. voltage
d. speed and voltage
Q. In D.C. generators, current to the external circuit from armature is given through
a. commutator
b. solid connection
c. slip rings
d. none of above
Q. If B is the flux density, I the length of conductor and v the velocity of conductor, theninduced e.m.f. is given by
a. Blv
b. Blv2
c. Bl2v
d. Bl2v2
Q. Which of the following could be lamina-proximately the thickness of laminations of aD.C. machine ?
a. 0.005 mm
b. 0.05 mm
c. 0.5 m
d. 5 m
Q. 63. Satisfactory commutation of D.C. machines requires
a. brushes should be of proper grade and size
b. brushes should smoothly run in the holders
c. smooth, concentric commutator properly undercut
d. all of the above
Q. While applying Fleming's right-hand rule to And the direction of induced e.m.f., the thumb points towards
a. direction of induced e.m.f.
b. direction of flux
c. direction of motion of the conductor if forefinger points in the direction of generated e.m.f.
d. direction of motion of conductor, if forefinger points along the lines of flux
Q. For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f. ?
a. Lap winding
b. Wave winding
c. Either of (a) and (b) above
d. Depends on other features of design
Q. If B is the flux density, I the length of conductor and v the velocity of conductor,then induced e.m.f. is given by
a. Blv
b. Blv2
c. Bl2v
d. Bl2v2