Which of the following materials can a capacitive sensor detect at the greatest distance?

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Capacitive sensing works by measuring changes in capacitance as a target enters the sensor’s electric field. The amount of change depends on how strongly the material disturbs that field, which relates to its ability to store charge and conduct electricity. Metal, being a conductor, perturbs the field most, producing a larger capacitance change even when the object is farther from the sensing element. Insulating materials like plastic or wood have lower dielectric constants, so they cause smaller changes and must be closer to be detected. Liquids can have high dielectric constants too, but the strong field disturbance from a metal typically allows detection at the greatest distance. So metal is detected at the farthest distance by a capacitive sensor.