Electric Motors Flashcards

All 6 cards in this deck

Why does a current-carrying coil in a magnetic field rotate in an electric motor?

The current flows in opposite directions on opposite sides of the coil, so the forces on those sides act in opposite directions, giving a turning effect.

What is the job of the split-ring commutator in a d.c. motor?

It reverses the current in the coil every half turn, so the coil keeps rotating in the same direction.

What is the job of the brushes in an electric motor?

They keep an electrical contact between the circuit and the rotating commutator, so current can flow in the spinning coil.

Name three ways to increase the turning effect of an electric motor.

Increase the current, use more turns on the coil, use a stronger magnetic field (or add an iron core).

How can the direction of rotation of a d.c. motor be reversed?

Reverse the current (swap the supply connections) or reverse the magnetic field (swap the magnet poles).

True or false? Without a split-ring commutator the coil of a d.c. motor would keep turning in the same direction.

False. It would stop or rock back and forth, because the forces would turn it back after half a turn.