DC motor. Image credit kostov-motors.com

ZIMSEC O Level Combined Science Notes: Experiment: Demonstrating that an electric wire moves in a magnetic field

  • A DC motor converts direct electric current into kinetic energy
  • It has a stator
  • Stator-a stationary magnet found within a DC motor
  • It also has a many coils wound on an armature
  • This is called a rotor
  • The coils are mounted on an axle which rotates in a magnetic coil
The internal components of a DC Motor. Image credit blogspot.com

The internal components of a DC Motor. Image credit blogspot.com

  • Each end of the coil is connected to the half of a split ring
  • The split ring is also known as a commutator
  • The commutator turns with the coil and makes contact with the two¬†carbon brushes
  • That it press lightly against the commutator split rings
  • Current is fed into the coil through the carbon brushes
  • The coil rotates until it is in vertical position
  • Its momentum (inertia) carries it past the vertical position
  • The two halves change contact from one brush to another
  • The direction of current is now reversed in the coil
  • The other half is also forced downwards thus maintaining rotation in one direction
  • Real world motors have a more sophisticated design but they still operate on the same principle
  • Some of these modifications include:
  • many turns in the coil,
  • A soft iron cylinder round which coils are wound
  • The coil and this core are known as an armature
  • A strong magnet
  • DC motors are used where variation in speed is needed
  • For example electric cars and trains
  • They are also used in toys and drones

Uses of Motors

  • Motors be they DC motors or AC motors (AC motors are beyond the scope of the O level syllabus) have a number of uses
  • They are used to drive devices such as:
  • pumps in mines and on farms
  • lifts in buildings
  • to power electric lawnmowers
  • electric drills
  • electric saws
  • Motors can also be found:
  • in fans
  • In washing
  • electric cars

To access more topics go to the Combined Science Notes page.