How do those lamps that switch on/off when you touch them work?
79988
It's magic!!   j/k\n\nTouch-sensitive lamps almost always use a property of the human body -- its capacitance. The word "capacitance" has as its root the word "capacity" -- capacitance is the capacity an object has to hold electrons. The lamp, when standing by itself on a table, has a certain capacitance. This means that if a circuit tried to charge the lamp with electrons, it would take a certain number to "fill it." When you touch the lamp, your body adds to its capacity. It takes more electrons to fill you and the lamp, and the circuit detects that difference. It is even possible to buy little plug-in boxes that can turn any lamp into a touch-sensitive lamp. They work on the same principle.
1121249
Fireflies produce light via a chemical reaction consisting of Luciferin (a substrate) combined with Luciferase (an enzyme), ATP (adenosine triphosphate) and oxygen. When these components are added, light is produced. \nThere are several theories on how fireflies control the "on" and "off" of their photic organs. However, the exact mechanism(s) has yet to be worked out. The "Oxygen Control Theory" is based on the firefly turning on and off its light by controlling the oxygen supply to the photic organ for use in the chemical reaction. The "Neural Activation Theory" hypothesizes that fireflies have neural control of structures called "tracheal end cells" which, upon stimulation, may release a messenger molecule in the photic organ which initiates the activation of the chemical reaction. Regardless of how fireflies control the "on" and "off" of their bioluminescence, the production of light in the above manner is very efficient. I think fireflies, or "lightning bugs" are amazing...another little demonstration of God's wild imagination.
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I'm not able to give a _complete_ description...  But as far as I know, a Reuter lamp is just a laboratory light source, that uses an ordinary light bulb (along with some fancy optics) to produce a focused (or collimated) beam of light that can be used for the sort of experiments done in first year Physics lab courses.  Some have cooling fans to keep the lamp cool despite the heating from the light bulb.  Essentially, it's just a fancy flashlight on a stick.
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Turn on one light bulb and leave it on for a while. Turn it off\nTurn on a second light bulb and leave it on. Go up stairs.\nThe second switch obviously turns on the bulb that is on.\nThe first switch (you turned on then off) is for the lightbulb that is NOT ON but is warm from being used. \nThe  3rd switch obviously is the one for the unlit lightbulb that's cold.
1176231
Generally, light is created when energy is released, usually in the form of heat. The reason a light bulb works is because electricity (energy) is forced through something with higher resistance (the filament inside the bulb). This creates heat and as a by product, light.
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Light Emitting Diodes and How They Work.\n\nhttp://electronics.howstuffworks.com/led.htm
172519
Sorry....that is not correct.  LCD's do NOT emit light.\n\n\nYou see LCD technology does not itself emit light. you either must have enough ambiant light to see, or it must be 'back-lit'. The Technology formmerly used to do this was CCFL or Cold Cathode Forescent Lamp, these failed in 2 different ways as they aged.\n\n1. the light would get darker as it aged. Some would even change color therby messing-up the colors the display rendered.\n\nand\n\n2. As the bulb ages, it requires more and more power to engergize it. Eventually it will reach a point where the amperage required to start the lamp, will exceed the capacity the circut it is on can provide and simply not light.\n\nIf you've ever seen this, or suspect that this is your problem (display won't light, or goes dark shortly after starting,) simply shine a bright light source directly into the display, you should see faintly whatever the desktop was diplaying at the time.....or your desktop if it never came on to begin with.\n\nCurrent Backlight technology uses white LED lights....far better.\nthe BEST ones use 3 LED lights....1 each of Red Blue and Green, much much better at displaying the full color spectrum.\n\nHope that helps !\n\nPS: the FLASHLIGHT you have.....is an LED flashlight, I would wager. I have one too, they're great !  $27 bucks though.\n\nPPS: more like 100,000 hours.\n\n\nto poster below....the current back-lighting method IS LED, the fact that it is also used in Thin Film Transister Displays does not really make a difference to this question.\ncheck your facts. oh and your 'plasma' info is waaaaaay off.\none year!  ha.
1097537
yes there is a little switch that gets pressed and it turns the light off
715746
on a 4 pin tube there is a small filament at each end cap, this coil connects the 2 pins on one end together (and there is a second filament coil at the other end).\n\nthe filament warms the tube, which makes it easier to strike (turn on). the following diagram should help (labels in spanish)\nhttp://en.wikipedia.org/wiki/Image:Fluorescente.png\nFilamento = filament\nreactancia inductiva = inductive resistance (ballast)\ncebador = starter\ncondensador = capacitor\ncontacto bi-metallica = bi-metallic contact\n\n\nhttp://en.wikipedia.org/wiki/Flourescent_tube
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These are specially designed light bulbs that have had their light output calibrated to a standard source at NIST (or maybe some other standards organization). They must be operated at a specified voltage potential. They usually cost an arm and a leg, have a limited lifetime (the filament evaporates over time changing its characteristics and also plating the glass of the bulb with a thin film of metal) and are only as stable as the voltage/current supply you power it with. You must also take care to never touch the glass with bare skin or anything else that might deposit contaminants.\n\nYou also have to be very careful not to touch the glass with bare skin or any other contaminants.
26356
well you have to turn them on first then it is all on from then on.
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The starter completes an electric circuit to heat the mercury inside the lamp so that current can flow between the electrodes easier -- once the light is going the starter opens, effectively removing itself from the circuit until the lamp is turned off again.\n\nThe ballast is basically a step-up transformer that converts the 110 vac husehold power to about 400 vac, which is enough to cause current to flow betweent he electrodes of the lamp once the filaments have heated the mercury vapor enough.\n\nModern systems do not require a starter, but instead use a more advanced ballast transformer which can perform both starting and driving duties.\n\nThanks for asking this question!  I remember those old ballast-and-starter systems from when I was in the Navy.  I never knew exactly how they worked back then, but now that you have asked this question I went and looked it up and now I do!
343350
with the aid of a ballast which controls current to each side of the bulb and the bulb is filled with a luminescent gas that when heated will illuminate
176518
Light bulb uses light waves.
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u can use switchs to power each one at a time but u ll need to place them in a parallel format cause using serial means u have to power the first bulb to be able to light any other ,other than that u can use relays and connect them in a way to have the light going in a sequence
177665
Here you go...\n\nhttp://www.electronicsforu.com/EFYLinux/circuit/dec2003/CI-01-night-lamp.pdf
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Compact Fluorescent Lamps\n\n  ************************************************************************\n  *                  COMPACT FLUORESCENT LIGHT BULBS                     *\n  *                                                                      *\n  *                       **** Version 1.10 ****                         *\n  *                                                                      *\n  *                      Copyright (C) 1996, 1999                        *\n  *                        Samuel M. Goldwasser                          *\n  *                        Donald L. Klipstein                           *\n  *                                                                      *\n  *        Corrections or suggestions to: sam@stdavids.marconimed.com    *\n  *                                       don@misty.com                  *\n  *                                                                      *\n  *                     --- All Rights Reserved ---                      *\n  *                                                                      *\n  *    Reproduction of this document in whole or in part is permitted    *\n  *    if both of the following conditions are satisfied:                *\n  *                                                                      *\n  *     1. This notice is included in its entirety at the beginning.     *\n  *     2. There is no charge except to cover the costs of copying.      *\n  *                                                                      *\n  ************************************************************************\n\n...\n\n8.  Like other fluorescents, operation at cold temperatures (under around\n    50 degrees F) may cause reduced light output or erratic operation.\n    Some models work fairly well down to about 35 degrees F, others may\n    get noticeably dim below 60 degrees F.  The optimum temperature range\n    of a particular lamp may vary with burning position, generally\n    preferring cooler temperatures if operated base-down.\n    Compact fluorescents may also not like excessive heat.  Some ballasts\n    are unreliable in ambient temperatures much over 120 degrees F.  This\n    is sometimes a problem in enclosed or recessed ceiling fixtures if\n    heat in the fixture builds up.