Materials exhibiting zero value of resistivity are known as ____________ ?

Related Mcqs:

1. The resistivity of water should not be less than_____________?

   A. 10 Q m B. 100 Q m C. 1000 Q m D. 2000 Q m...

2. Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors ?

   A. Copper B. Aluminium C. Steel D. Cast-iron...

3. Hot rolled sheets have ___________ value of permeability?

   A. zero B. low C. high D. none of the above...

4. The value of exciting or magnetizing current depends upon which of the following factors ?

   A. Total m.m.f. required B. The number of turns in the exciting winding C. The way in which the winding is distributed D. All of the above...

5. In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?

   A. 10 m/s B. 20 m/s C. 30 m/s D. 40 m/s...

6. D.C. machines designed with a large value of air gap length have_____________?

   A. worst, ventilation B. poor ventilation C. better ventilation D. none of the above...

7. The efficiency of a machine should be as ____________ as possible to reduce the operating cost?

   A. high B. low C. either of the above D. none of the above...

8. ____________ is the common method of applying brushes to the commntator?

   A. Radial B. Trailing C. Reaction D. All of the above...

9. The mcrease in heat dissipation by air blasts is due to increase in______________?

   A. conduction B. convection E. radiation D. any ofthe above...

10. When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of_____________?

    A. short pitch B. full pitch C. either of the above D. none of the above...