Trent builds a model electric motor. When he connects a battery to the motor, the motor spins through a half rotation and stops. Which is the most likely solution to the problem?

A simple DC motor’s commutator reverses the current in the armature every half rotation, so the magnetic forces keep the motor turning in the same direction. If the current does not reverse, the turning force can change direction and the motor may stop after half a turn. Therefore, checking the commutator is the most likely solution; adding more coils would not fix the missing reversal.

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