What are brushes in DC motors used for?

What are brushes in DC motors used for?

• A. Provide electrical contact with the rotating commutator
• B. Generate the rotating magnetic field
• C. Control the motor's speed
• D. Cool the motor windings

Answer: (A)

Brushes provide the electrical connection between the stationary power supply and the rotating armature by pressing against the rotating commutator. This contact lets current flow into the rotor windings, and the commutator switches which winding segments are connected to the supply as the rotor turns, so the torque keeps driving rotation in the same direction. The magnetic field itself comes from the stator (or field windings) and the current in the rotor—not from the brushes. Brushes don’t set motor speed directly, nor do they cool the windings; those roles come from voltage control and cooling systems, while the brushes mainly enable electrical transfer to the moving parts.

Brushes provide the electrical connection between the stationary power supply and the rotating armature by pressing against the rotating commutator. This contact lets current flow into the rotor windings, and the commutator switches which winding segments are connected to the supply as the rotor turns, so the torque keeps driving rotation in the same direction. The magnetic field itself comes from the stator (or field windings) and the current in the rotor—not from the brushes. Brushes don’t set motor speed directly, nor do they cool the windings; those roles come from voltage control and cooling systems, while the brushes mainly enable electrical transfer to the moving parts.