What is the purpose of a rotary switch?

A rotary switch serves the primary function of selecting one or multiple circuits through its rotating mechanism. When the switch is turned, it connects a single common terminal to one of several different output terminals, allowing the user to choose a specific circuit or setting from multiple options. This makes rotary switches particularly useful in various applications where multiple configurations are needed, like selecting different functions on a piece of equipment.

The other options describe different types of switches or devices. For instance, opening and closing a circuit with a button pertains more to a push-button switch, which operates with a simple on/off action. Detecting presence without contact describes capacitive or inductive sensors, which do not involve manual selection of circuits. Controlling high-level loads typically refers to switches designed to handle large current applications, which might not specifically be rotary switches but rather contactors or relay switches designed for that purpose. Thus, the focus of the rotary switch on selecting circuits distinctly aligns with its intended use.