In shunt dc motor the direction of rotation of the motor will reversed. When
A. either field terminals are reversed or armature terminals are reversed.
B. only armature terminals are reversed.
C. only field terminals are changed.
D. none of above.
Answer: A
Share your understanding of this question with the correct explanation.
In a shunt DC motor, the direction of rotation can be reversed when either the field terminals or the armature terminals are reversed.
The direction of rotation of a DC motor is determined by the interaction between the magnetic fields produced by the field winding (field terminals) and the armature current flowing through the armature winding (armature terminals).
Reversing the field terminals will reverse the direction of the magnetic field produced by the field winding. This change in the magnetic field direction will affect the overall torque production and consequently reverse the rotation direction of the motor.
Similarly, reversing the armature terminals will reverse the direction of the armature current. Since the armature current interacts with the magnetic field to produce the torque, reversing the armature current direction will also reverse the rotation direction of the motor.
Therefore, to reverse the rotation direction of a shunt DC motor, either the field terminals or the armature terminals need to be reversed. This is why the correct answer is A: either field terminals are reversed or armature terminals are reversed.