What is the purpose of a split ring commutator in a DC motor?

The purpose of a split ring commutator in a DC motor is to reverse the current direction flowing through the coil each half turn. This is crucial because, in order for the motor to continue rotating in the same direction, the current must change direction at the appropriate times in relation to the magnetic field produced by the stationary magnets or electromagnets in the motor.

As the coil rotates within this magnetic field, the commutator ensures that the current's direction alters when the coil reaches the vertical position, thus maintaining continuous rotational motion. Without this switching mechanism, the coil would experience a moment where the forces acting on it would stop, preventing the motor from operating effectively.

In context, converting AC to DC pertains to different applications in electrical systems, sustaining a magnetic field does not specifically relate to the function of the commutator, and enhancing starting torque involves other aspects of motor design such as the winding configuration and power supply. These elements, while important in motor operation, do not specifically describe the direct function of the split ring commutator itself.