Computer Programming MCQs

5739 MCQs  (Page 52 of 574)

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
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
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
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
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