To reverse a DC motor safely, you should

To reverse a DC motor safely, you should

• A. Reverse either the armature polarity or the field, but not both
• B. Reverse both armature and field
• C. Reverse neither
• D. Stop and restart

Answer: (A)

A DC motor’s rotation is determined by the relative polarity between the armature current and the magnetic field. If you swap the polarity on the armature, the torque reverses and the motor spins in the opposite direction. If you swap the polarity of the field, the same reversal occurs. Reversing both at the same time leaves the relative polarity the same, so the direction doesn’t change. So, to reverse safely you change the polarity of just one winding (either the armature or the field) using a proper reversing switch or relays, ideally with the power off and a controlled transition to avoid large current or mechanical stress.

A DC motor’s rotation is determined by the relative polarity between the armature current and the magnetic field. If you swap the polarity on the armature, the torque reverses and the motor spins in the opposite direction. If you swap the polarity of the field, the same reversal occurs. Reversing both at the same time leaves the relative polarity the same, so the direction doesn’t change. So, to reverse safely you change the polarity of just one winding (either the armature or the field) using a proper reversing switch or relays, ideally with the power off and a controlled transition to avoid large current or mechanical stress.