Question

An electric motor is a device which transforms :

(a) mechanical energy to electrical energy

(b) heat energy to electrical energy

(c) electrical energy to heat energy only

(d) electrical energy to mechanical energy

Answer 1

Answer is d) electrical energy to mechanical energy.

Electric motors make mechanical energy through the interaction between magnetic fields.

Take two magnets and attempt to push their North poles together. There will be a repulsive force that resists this motion. Move one North pole near the other magnet's South pole. There will be an attractive force that pulls them together.

Magnetic fields can be generated by passing a current through a wire. Winding that wire into a coil intensifies the field. Wrapping the coil around an iron core will intensify it further. One end of the coil will be North, the other South. Reverse the flow of current through the coil. The magnetic poles will swap. Place two separate coils near each other and arrange them so one turns while the other is fixed. Then make arrangements for the current in the moving coil to reverse just as the opposite poles are about to line up.