![]() The word "capacitance" has as its root the word "capacity" - capacitance is the capacity an object has to hold electrons. Touch-sensitive lamps almost always use a fourth property of the human body - its capacitance. There are even small LCD TVs that have a conductive neck strap so that the user acts as the antenna! Some touch-sensitive switch designs simply look for a change in radio-wave reception that occurs when the switch is touched. That's because the human body makes a pretty good antenna. Radio reception - You may have noticed that, when you touch an antenna, the reception gets better on a TV or radio.By placing two contacts very close together, your finger can close the circuit when you touch it. Resistance - The human body, being made mostly of water, conducts electricity fairly well.The motion-sensitive lamps you see on people's patios also sense the heat of the human body. ![]() ![]() These buttons, of course, don't work if you have cold hands. Many elevators therefore use buttons that are sensitive to the warmth of the human finger. Temperature - The human body is generally warmer than the surrounding air. ![]()
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