In a DC motor, which component reverses current in the windings to produce rotation?

In a DC motor, which component reverses current in the windings to produce rotation?

• A. Armature
• B. Commutator
• C. Field Frame
• D. Brushes

Answer: (B)

The action being tested is how a DC motor keeps rotating by reversing the current in the windings at the correct moment. The commutator does this by acting as a split-ring switch attached to the rotor windings. As the rotor turns, the commutator pauses and then swaps the connection of each winding to the supply via the stationary brushes, effectively reversing the current through the windings every half turn. This reversal keeps the torque direction the same, so rotation continues smoothly. The brushes simply provide the electrical contact between the stationary circuit and the moving commutator; they don’t reverse current themselves. The armature is the rotating set of windings that experiences the magnetic force, but the reversal of current comes from the commutator. The field frame provides the magnetic field, either from permanent magnets or electromagnets, and does not perform the reversal.

The action being tested is how a DC motor keeps rotating by reversing the current in the windings at the correct moment. The commutator does this by acting as a split-ring switch attached to the rotor windings. As the rotor turns, the commutator pauses and then swaps the connection of each winding to the supply via the stationary brushes, effectively reversing the current through the windings every half turn. This reversal keeps the torque direction the same, so rotation continues smoothly.

The brushes simply provide the electrical contact between the stationary circuit and the moving commutator; they don’t reverse current themselves. The armature is the rotating set of windings that experiences the magnetic force, but the reversal of current comes from the commutator. The field frame provides the magnetic field, either from permanent magnets or electromagnets, and does not perform the reversal.