What's the underlying principle of a direct current motor?

The underlying principle of a direct current motor is the interaction between magnetic fields and electric current to generate rotational motion.

A direct current (DC) motor operates based on the fundamental principles of electromagnetism and the law of interaction between magnetic fields. When an electric current passes through a wire within a magnetic field, it experiences a force. This force is what causes the rotational motion in a DC motor.

The key components of a DC motor include a stator, rotor, commutator, brushes, and a power supply. The stator is the stationary part of the motor that provides a constant magnetic field. The rotor, also known as the armature, is the rotating part of the motor. It contains wire coils that become electromagnets when current is passed through them. The commutator and brushes work together to ensure that the current direction in the rotor coil is always in the correct direction to maintain rotation.

The operation of a DC motor begins when a direct current is supplied to the motor. This current flows through the brushes to the commutator and then to the rotor coils. As the current passes through the rotor coils, they become electromagnets. According to Fleming's Left-Hand Rule, the interaction between the magnetic field of the stator and the magnetic field of the rotor creates a force that pushes the rotor to rotate.

The commutator plays a crucial role in maintaining the rotation of the rotor. It is a split ring that reverses the direction of the current in the rotor coils every half rotation. This ensures that the force on the rotor always acts in the same direction, maintaining continuous rotation.

In summary, a DC motor utilises the principles of electromagnetism and the interaction of magnetic fields to convert electrical energy into mechanical energy. The continuous rotation of the rotor, which is the output of the motor, is achieved through the clever design of the commutator and brushes, which ensure the current in the rotor coils is always in the correct direction.