Lighting has changed by leaps and bounds since the invention of the light bulb in the late 19th century. It used to be that you had to pull a chain to activate a light fixture, but today we can activate our lights with a light touch of a finger. It can be a fun jest to ask someone how they think a touch lamp works, as they will probably stutter and stumble as they conjure up a far-out explanation. Touch lamps may seem mysterious, but they operate under well-explained scientific principles which will be discussed in this guide.
It is important to note that several different methods have been used in touch lamps. The first attempt at achieving touch-activation of a bulb was to use the heat given off by the human body. Sensor strips hidden inside the casing of the lamp can sense the temperature change when the lamp is touched. As long as your fingers are not cold, the lamp will work reliably with every firm press. Buttons inside of elevators are also known for using such technology.
The metal frame of any lamp has a certain capacitance. The term capacitance refers to the amount of electrons that an object / material can hold. When you touch a metal lamp, your body adds to the capacitance of the lamp. A sensor within the touch lamp can sense this difference, thus activating or turning off the lamp upon a touch. Most touch sensitive lamps these days utilize capacitance to govern their switches.
Completing the Circuit:
The human body is mostly composed of water which can, under the right conditions, conduct enough electricity to turn on a switch. When your finger touches two metal contacts, a circuit can be completed and the lamp can turn on. The downside with this method is that you have to touch the contact area to activate the lamp. This method is not commonly used on lamps.
Touch Lamp Dimmers:
A good deal of touch lamps have the ability to operate on different intensities: low, medium and high. To make this possible, the light bulbs flicker on and off at different speeds. You may not notice it, but many light sources have light bulbs which flicker on/off very fast. In most cases the flickering is faster than the eye can see. For example, a light bulb which has a full brightness when flickered 120 times per second will have 1/2 intensity when operating at 60 flickers per second.
Some Advantages of Touch Lamps:
Mechanical switches can break down over time, getting filled with scum and dirt over the course of years. A touch lamp has no moving parts to speak of, making them extremely reliable. They also eliminate the pain caused by reaching underneath a lamp shade and getting burned on the light bulb while feeling for a pull cord. Simply touching any metal portion of a touch lamp will result in immediate activation.
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