How can you reverse the rotation of a single-phase motor?

Reversing the rotation of a single-phase motor can be effectively accomplished by shifting the brushes or reversing the wires. This process alters the direction of the magnetic field created within the motor, which ultimately changes the rotational direction of the rotor.

In many single-phase motors, especially those using split-phase or capacitor-start designs, the direction of the magnetic field is crucial for determining the rotation. By adjusting the wires or the position of the brushes (in brush-type motors), you can effectively flip the polarity of the magnetic field. This shift changes the interaction between the stator and rotor, resulting in the rotor spinning in the opposite direction.

Other methods listed in the options might not be suitable for effectively reversing the motor's rotation. Changing the voltage supply does not directly affect the rotational direction. Interchanging two wires could work, but it generally applies to three-phase motors rather than single-phase motors. Increasing current will not impact the direction of rotation; it may only affect the torque or power of the motor. Thus, the most practical and relevant approach for a single-phase motor is to either shift brushes or reverse specific wiring configurations.