What is a common application for using a proximity sensor?

A proximity sensor is commonly used to detect the presence of objects without physical contact. This functionality is central to various applications, such as in automation systems where sensing an object's location is crucial for operation. For instance, in manufacturing, proximity sensors can help in automatically detecting parts on an assembly line, ensuring that machines operate efficiently and without interruption.

In addition to industrial applications, proximity sensors are also widely used in consumer electronics, such as in smartphones to turn off the display when the phone is held to the ear during a call. This ability to detect objects enhances user experience by providing convenience and safety.

The other options—measuring temperature, controlling voltage levels, and measuring weight—do not align with the primary function of a proximity sensor, which is focused on object detection rather than other types of measurements or controls.