Explain how forces on a current-carrying coil make a simple DC motor turn and why a split-ring commutator is needed.

Question

Accepted Answer

Opposite magnetic forces on the coil form a turning couple; the split ring reverses coil current every half-turn so the torque keeps the same rotational sense. Current in opposite coil sides runs in opposite directions within the field. The magnetic forces are opposite and separated, producing a torque. After half a turn the commutator reverses current, preventing torque reversal. Electrical energy becomes mechanical energy with some heat and sound losses.

Motor energy pathway

Explain how forces on a current-carrying coil make a simple DC motor turn and why a split-ring commutator is needed.

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