Electronics Engineering (ELEX) Board Practice Exam

Capacitive sensors are primarily designed to detect changes in capacitance that occur when nearby objects, such as a human finger or other conductive materials, influence the electric field around the sensor. When an object comes within proximity of the sensor, it alters the capacitance, which is the ability of the sensor to store an electrical charge. This change in capacitance can be measured and interpreted as an input signal, allowing the sensor to detect presence, motion, or touch.

This principle of operation makes capacitive sensors widely utilized in various applications, including touchscreens, proximity sensors, and liquid level sensing, among others. The detection relies on the principles of electrostatics, where the movement of nearby conductive or dielectric materials modifies the sensor's electric field, leading to changes in capacitance that are measurable and informative for the system.