A centrifugal switch is used in a ____.

A centrifugal switch is primarily used in capacitor-start motors to disconnect the capacitor from the circuit after the motor has reached a certain speed. This is essential for ensuring that once the motor is up to speed, the capacitor, which helps in providing an extra phase to start the motor, is no longer needed for operation. The centrifugal switch relies on the centrifugal force generated by the rotor's movement to operate, allowing for the automatic disconnection of the starting circuit.

In the context of the options provided, while centrifugal switches might also be found in various types of motors, they are particularly associated with capacitor-start motors, as that is where the switch plays a crucial role in enhancing efficiency and protecting the motor from potential damage caused by the capacitor remaining in the circuit too long after startup.