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 conductorB. lines of force C. either of the…
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…
In D.C. generators the pole shoes are fastened to the pole core by_____________? A. rivetsB. counter sunk screws C. brazing D. welding
Fleming’s right-hand rule regarding direction of induced e.m.f., correlates__________? A. magnetic flux, direction of current flow and resultant forceB. magnetic flux, direction of motion and the direction of e.m.f. induced C. magnetic field strength, induced voltage and current D. magnetic…
In case of D.C. machines, mechanical losses are primary function of____________? A. current B. voltageC. speed D. none of 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
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 windingB. Wave winding C. Either of A. and B. above D. Depends…
In D.C. generators, the cause of rapid brush wear may be___________? A. severe sparking B. rough commutator surface C. imperfect contactD. any of the above
The bearings used to support the rotor shafts are generally______________? A. ball bearings B. bush bearings C. magnetic bearmgs D. needle bearings
In lap winding, the number of brushes is always_____________? A. double the number of polesB. same as the number of poles C. half the number of poles D. two