Which of the following is not a component of a limit switch?

A limit switch typically consists of several key components, and understanding these components helps clarify why the correct answer identifies the optical sensor as not being part of a standard limit switch.

The actuating mechanism is a critical element of a limit switch, as it is responsible for detecting the presence of an object or the position of a machine part. This mechanism can be a mechanical arm or lever that physically interacts with the object being monitored, and its activation triggers the limit switch's internal circuitry.

Contacts are another essential component of a limit switch. They are the electrical parts that open or close an electrical circuit when the actuating mechanism is triggered. This is how limit switches send signals to control systems, activating or deactivating machinery, which is vital for safety and operational control in various applications.

On the other hand, an optical sensor operates differently. Optical sensors use light (usually infrared) to detect objects without needing physical contact. While they serve similar functions in detecting positions or object presence, they are a distinct type of sensor and not a traditional component of limit switches.

Thus, the optical sensor does not fit into the category of components that define a limit switch, making it the correct response in this scenario.