What is the basic operation of a moisture sensor?

A moisture sensor primarily functions by changing its resistance based on the moisture levels in the environment or in a specific material, such as soil. This change in resistance is often due to the material's conductivity varying with moisture content. When moisture is present, ions in the water can enhance the conductivity of the sensor, which alters the resistance reading. This characteristic allows the moisture sensor to effectively indicate the level of moisture, making it a valuable tool in applications such as agriculture, environmental monitoring, and home automation systems.

The other options pertain to different sensor functions. For instance, measuring temperature is the primary role of a temperature sensor, while detecting light intensity is the function of a light sensor. Regulating voltage in circuits typically involves components like voltage regulators rather than moisture sensors. Thus, the correct choice highlights the specific operation related to moisture levels, which is the fundamental purpose of a moisture sensor.