Recap - Electromagnetism

A magnet may be attracted or repelled by

• another magnet

• electric current

• resistor

• dynamo

Many machines we use today are powered by

• thermal energy

• sound energy

• motors

• dynamos

An electric motor changes electric energy into

• potential energy

• thermal energy

• light energy

• kinetic energy

The magnetic fields of a coil and a permanent magnet

• attract each other

• repel each other

• combine with each other

• remain with each other

To keep the coil rotating, current is reversed every half-cycle with the help of

• carbon brushes

• capacitor

• commutator

• spring contacts