Electric motors and generators are practical applications of electromagnetic principles, particularly the motor effect and electromagnetic induction.

Electric Motors

Electric motors convert electrical energy into mechanical energy using the motor effect. When a current-carrying conductor is placed in a magnetic field, it experiences a force (given by \( \vec{F} = I\vec{L} \times \vec{B} \)).

In a simple DC motor:

• Current flows through a coil placed in a magnetic field.
• The resulting force causes the coil to rotate.
• A commutator ensures the current direction reverses each half-turn, maintaining rotation.

Applications: Fans, washing machines, electric vehicles, drills, elevators.

Generators

Generators convert mechanical energy into electrical energy based on Faraday’s law of electromagnetic induction. When a coil rotates in a magnetic field (or vice versa), a voltage is induced across its ends.

In a simple generator:

• A coil rotates between the poles of a magnet.
• Magnetic flux through the coil changes with time.
• This change induces an alternating current (AC) in the coil.

Applications: Power plants, wind turbines, hydroelectric stations, backup power systems.

Thus, motors and generators are inverse processes — motors use current to produce motion, while generators use motion to produce current.

Written by Thenura Wickramaratna