A capacitive sensor relies on what principle to sense an object's presence?

A capacitive sensor operates based on the principle of capacitance, which is heavily influenced by the dielectric properties of materials. When a capacitive sensor is placed near an object, the sensor detects changes in capacitance caused by the presence of that object. This occurs because the material of the object affects the electric field between the sensor’s plates or alters the distance between those plates.

The presence of the object changes the dielectric constant of the space between the plates of the capacitive sensor. Different materials have different dielectric constants, which directly influences the sensor's ability to detect distance and presence. When an object with a higher dielectric constant comes close to the sensor, the capacitance increases, which can then be measured and interpreted as the presence of the object.

In contrast, the other principles mentioned, such as magnetism, resistance, and conductance, relate to different types of sensors or physical phenomena and are not the basis on which capacitive sensors detect objects.