Torque developed by a D.C. motor depends upon_____________?
A. magnetic field
B. active length of the conductor
C. current flow through the conductors
D. number of conductors
E. radius of armature
F. all above factors
The direction of rotation of a D.C. series motor can be changed by___________?
A. interchanging supply terminals
B. interchanging field terminals
C. either of A. and B. above
D. None of the above
With the increase in temperature, the speed of DC series motor______________?
A. decreases
B. increases
C. remain same
D. none of the above
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens____________?
A. this will make armature to take heavy current, possibly burning it
B. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
C. nothing will happen to motor
D. motor will come to stop
Which of the following motor has the poorest speed regulation ?
A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor
The speed of a D.C. shunt motor can be increased by_______________?
A. increasing the resistance in armature circuit
B. increasing the resistance in field circuit
C. reducing the resistance in the field circuit
D. reducing the resistance in the armature circuit
Which of the following motor is preferred for operation in highly explosive atmosphere ?
A. Series motor
B. Shunt motor
C. Air motor
D. Battery operated motor