When an electric current passes through the coil in a motor, according to Ampère’s law, the current generates a magnetic field.

　　When current flows through the windings of a motor, Ampère’s law dictates that the current generates a magnetic field. In a DC motor, this magnetic field interacts with the motor’s internal stationary magnetic field, which is produced by permanent magnets or electromagnets.

　　The interaction of magnetic fields exerts a force on the coil, which is known as the electromagnetic force or Ampère force.

　　When the direction of current in the coil changes—typically achieved through a commutator and brushes—the direction of the electromagnetic force acting on the coil also reverses, enabling the coil to rotate continuously.

　　In a 3.3 V DC motor, despite the low supply voltage, a well‑designed motor structure and appropriate current control can still generate sufficient electromagnetic torque to drive the rotor.

　　The commutator is a rotating component composed of multiple metal segments, each of which is connected to one of the motor’s windings.

　　The brushes are mounted on the motor and remain in contact with the commutator. As the motor rotates, the brushes make contact with different segments of the commutator, thereby reversing the direction of current flowing through the windings.

　　This commutation mechanism ensures that the motor can rotate continuously, preventing it from stalling due to a constant current direction in the windings.

　　A DC motor converts electrical energy into mechanical energy. When current flows through the coil, the resulting electromagnetic force causes the motor shaft to rotate, thereby driving the load.

　　During this process, electrical energy is consumed and converted into mechanical energy and a small amount of thermal energy.

　　The speed and torque of a 3.3 V DC motor can be adjusted by varying the input voltage or current, or by using an electronic speed controller.

　　By adjusting these parameters, the motor’s performance can be tailored to meet the requirements of various applications.

　　A 3V DC motor primarily consists of several major components: the stator, the rotor, the brushes, and the commutator.

　　The stator is the stationary part of the motor, primarily composed of main poles, armature windings, and end covers. The main poles are fitted with excitation windings, which generate the main magnetic field when energized.

　　The rotor is the rotating part of an electric motor, consisting of the armature core, armature windings, and a commutator. When current flows through the armature windings, they experience forces in the magnetic field, causing the rotor to rotate.

　　The brushes are mounted on the stator and maintain sliding contact with the commutator, thereby conducting current from the external power supply into the armature windings.

　　The commutator is connected to the armature winding and serves to convert the direct current supplied by the brushes into alternating current within the armature winding, thereby ensuring stable electromagnetic torque.

　　The operating principle of a 3V DC motor is based on Faraday’s law of electromagnetic induction and the left-hand rule. When a DC power source (such as a 3.3V battery) supplies current to the armature windings on the rotor via brushes and a commutator, an electric current flows through these windings. As a result, the armature windings experience a force in the magnetic field produced by the stator; this force is known as the electromagnetic force.

　　According to the left-hand rule, the direction of the electromagnetic force is perpendicular to the plane formed by the current direction and the magnetic field direction, and it acts in such a way as to induce a rotational tendency in the armature winding. When the electromagnetic force is sufficiently strong, the armature begins to rotate within the stator’s magnetic field, thereby driving the load to turn.

　　The commutator plays a crucial role during motor operation. It promptly reverses the contact position between the brushes and the armature windings whenever the current direction in the armature winding changes, ensuring that the current always flows in the correct direction and thereby generating a stable electromagnetic torque.