Red Seal Instrumentation and Control Technician Exam Prep 2026 – Complete Practice Test

A hygrometer is specifically designed to measure the humidity in the air. It can be either a mechanical device or an electronic sensor, and it directly relates to the measurement of moisture content in the atmosphere. Capacitive sensors are also used to measure humidity by assessing the change in capacitance that occurs as the humidity level changes. This capacity to measure humidity accurately makes these instruments essential in various applications, including HVAC systems, meteorology, and industrial processes.

In contrast, thermocouple sensors are primarily designed for temperature measurement, pressure transducers measure the pressure of gases or liquids, and infrared sensors are typically used to detect infrared radiation or measure temperature based on the emitted radiation. Consequently, they do not directly measure humidity, which highlights the specificity and relevance of hygrometers and capacitive sensors for this particular purpose.