Electric Motors Flashcards

All 5 cards in this deck

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

The forces on the two opposite sides of the coil act in opposite directions (one up, one down), giving a turning effect.

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

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

True or false? Without a split-ring commutator, the coil of a d.c. motor would carry on spinning in the same direction.

False. It would turn half a turn and then the forces would push it back, so it would just rock back and forth.

What are the brushes in an electric motor for?

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 (and speed) of an electric motor.

Increase the current, use a stronger magnet (greater flux density), and use more turns on the coil.