Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. 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
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. The bearings used to support the rotor shafts are generally
a. ball bearings
b. bush bearings
c. magnetic bearmgs
d. needle bearings
Q. In D.C. generators, the cause of rapid brush wear may be
a. severe sparking
b. rough commutator surface
c. imperfect contact
d. any of the above
Q. In lap winding, the number of brushes is always
a. double the number of poles
b. same as the number of poles
c. half the number of poles
d. two
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. 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,then induced e.m.f. is given by
a. Blv
b. Blv2
c. Bl2v
d. Bl2v2