What type of switch uses a rotary motion to open and close contacts?

A selector switch is designed specifically to utilize a rotary motion to open and close contacts. This type of switch allows the user to select different options or circuits by turning a knob or handle. Each position represents a different circuit connection, making it versatile for applications that require multiple operational modes. The rotary action is not only intuitive but also provides a clear indication of the selected setting compared to linear or toggle type switches.

In contrast, other switch types operate differently: an automatic switch usually relies on some form of sensor or timer and does not involve a manual rotary movement; a pushbutton switch operates with a simple press action; and a knife switch typically uses a rocking action to open or close circuits, which does not incorporate a rotary mechanism. Therefore, the defining characteristic of using rotary motion aligns specifically with the function of a selector switch.