In electric motors and electric generators, which part is responsible for transferring current from the power source to the commutator or from the slip rings to where the electricity is needed?

Brushes make sliding electrical contact with the commutator in a motor or with the slip rings in a generator. This contact transfers current between the stationary external circuit and the rotating part. The armature carries the coils, while the axle supports rotation and the magnet provides a magnetic field, so the correct choice is brush.

AI-written and checked against the verified answer.