What are the working principles of a DC motor?

A DC motor works by converting direct current electrical energy into mechanical energy through the interaction of magnetic fields.

In more detail, a DC motor operates based on the principle of electromagnetism discovered by Michael Faraday. He found that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force. This force is given by Fleming's Left-Hand Rule. The direction of the force is perpendicular to both the direction of the current and the magnetic field.

The main components of a DC motor are the stator, rotor (or armature), commutator, and brushes. The stator is the stationary part of the motor, which produces a magnetic field with either permanent magnets or electromagnetic windings. The rotor, on the other hand, is the rotating part of the motor. It has windings that are connected to a commutator, a type of rotary electrical switch. The brushes, usually made of carbon, provide the electrical connection to the rotor through the commutator.

When a DC voltage is applied to the motor, current flows through the armature windings. This current generates a magnetic field around the armature, which interacts with the magnetic field of the stator. According to Fleming's Left-Hand Rule, this interaction produces a force that causes the armature to rotate. The commutator ensures that the current direction in the armature windings is always such that the force on each side of the armature is always in a direction to cause rotation.

The speed of the motor can be controlled by varying the input voltage or the strength of the magnetic field. In general, the higher the voltage or the stronger the magnetic field, the faster the motor will rotate. Conversely, reducing the voltage or the magnetic field strength will slow down the motor.