In case of D.C. machines, mechanical losses are primary function of____________?

Related Mcqs:

1. In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when____________?

   A. r.p.m. is more than 300 B. r.p.m. is less than 300 C. number of poles is 4 D. number of poles is 2...

2. Brushes of D.C. machines are made of_________?

   A. carbon B. soft copper C. hard copper D. all of above...

3. For a D.C. machines laboratory following type of D.C. supply will be suitable___________?

   A. rotary converter B. mercury are rectifier C. induction motor D.C. generator set D. synchronous motor D.C. generator set...

4. 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...

5. Iron losses in a D.C. machine are independent of variations in_____________?

   A. speed B. load C. voltage D. speed and voltage...

6. Iron losses in a D.C. machine are independent of variations in______________?

   A. speed B. load C. voltage D. speed and voltage...

7. 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...

8. 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...

9. A D.C. generator works on the principle of____________?

   A. Lenz’s law B. Ohm’s law C. Faraday’s law of electromagnetic induction D. none of the above...

10. 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...