In which of the following device the generated emf and armature current are in the opposite directions?

Related Mcqs:

1. In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be_____________?

   A. almost negligible
   B. rated full-load current
   C. less than full-load current
   D. more than full-load current

2. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to

   A. 100% of the previous value
   B. 50% of the previous value
   C. 25% of the previous value
   D. 10% of the previous value
   E. none of the above

3. The current drawn by the armature of D.C. motor is directly proportional to__________?

   A. the torque required
   B. the speed of the motor
   C. the voltage across the terminals
   D. none of the above

4. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?

   A. a resistance is connected in series with armature
   B. a resistance is connected parallel to the armature
   C. armature is temporarily open circuited
   D. a high value resistor is connected across the field winding

5. If I2 be the armature current, then speed of a D.C. shunt motor is_______________?

   A. independent of Ia
   B. proportional to la
   C. varies as (Ia)
   D. varies as la

6. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?

   A. regenerative
   B. plugging
   C. dynamic braking
   D. none of the above
   E. any of the above

7. The armature voltage control of D.C. motor provides____________?

   A. constant torque drive
   B. constant voltage drive
   C. constant current drive
   D. none of the above

8. The armature voltage control of D.C. motor provides_____________?

   A. constant voltage drive
   B. constant current drive
   C. constant torque drive
   D. none of the above

9. When the armature of a D.C. motor rotates, e.m.f. induced is___________?

   A. self-induced e.m.f.
   B. mutually induced e.m.f.
   C. back e.m.f
   D. none of the above

10. Armature reaction in dc motor results___________?

    A. decrease in speed
    B. increase in speed
    C. short circuit
    D. open circuit