Eddy currents are induced in the pole shoes of a D.C. machine due to______________?

Related Mcqs:

1. In D.C. generators the pole shoes are fastened to the pole core by_____________?

   A. rivets
   B. counter sunk screws
   C. brazing
   D. welding

2. The function of pole shoes in the case of D.C. machine is______________?

   A. to reduce the reluctance of the mag¬netic path
   B. to spread out the flux to achieve uniform flux density
   C. to support the field coil
   D. to discharge all the above functions

3. In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?

   A. 4
   B. 8
   C. 16
   D. 32

4. 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

5. In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called____________?

   A. rotor
   B. stator
   C. field
   D. armature

6. In case of D.C. machine winding, number of commutator segments is equal to______________?

   A. number of armature coils
   B. number of armature coil sides
   C. number of armature conductors
   D. number of armature turns

7. 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

8. The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be_______________?

   A. E/2
   B. 2E
   C. slightly less than E
   D. E

9. The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?

   A. 2
   B. 4
   C. 6
   D. 8

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