True or False: Changing the direction of current flow to a universal motor changes its direction of rotation.

True or False: Changing the direction of current flow to a universal motor changes its direction of rotation.

• A. True
• B. False
• C. Sometimes true
• D. It depends on wiring

Answer: (B)

In a universal motor, the field winding and the armature winding are in series, so they share the same current. Reversing the supply polarity reverses both windings, but their relative polarity stays the same. The commutator then keeps the torque direction as designed, so the motor continues to rotate in the same direction. That’s why simply changing the direction of current flow does not change rotation direction. If you somehow reversed only one winding relative to the other, the rotation would flip, but with a standard universal motor (windings in series), reversing the current direction does not cause a change in rotation.

In a universal motor, the field winding and the armature winding are in series, so they share the same current. Reversing the supply polarity reverses both windings, but their relative polarity stays the same. The commutator then keeps the torque direction as designed, so the motor continues to rotate in the same direction. That’s why simply changing the direction of current flow does not change rotation direction. If you somehow reversed only one winding relative to the other, the rotation would flip, but with a standard universal motor (windings in series), reversing the current direction does not cause a change in rotation.