what type of light (Bulb) used in traffic lights? what is the life period for the bulb?
916913
On 10 December 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J.P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January 1869, injuring the policeman who was operating it.\n\nOptics and Lighting\nIn the mid 1990s, cost-effective traffic light lamps using light-emitting diodes (LEDs) were developed; prior to this date traffic lights were designed using incandescent or halogen light bulbs. Unlike the incandescent-based lamps, which use a single large bulb, the LED-based lamps consist of an array of LED elements, arranged in various patterns. When viewed from a distance, the array appears as a continuous light source.\n\nLED-based lamps have numerous advantages over incandescent lamps; among them are:\n\n    * Much greater energy efficiency\n    * Much longer lifetime between replacement, measured in years rather than months. Some of the longer lifetime is due to the fact that the light is an array which allows the light to be used even if some of the LEDs in the array are dead.\n    * Brighter illumination with better contrast even in direct sunlight.\n    * The ability to display multiple colors and patterns from the same lamp. Individual LED elements can be enabled or disabled, and different color LEDs can be mixed in the same lamp.\n    * Much faster switching.\n    * Instead of a sudden burn-out like incandescent-based lights, LEDs start to gradually dim out when they're past their prime, allowing transportation maintenance departments to be warned well in advance as to when to change the light.\n\nThe operational expenses of LED-based signals are far lower than equivalent incandescent-based lights. As a result, most new traffic light deployments in the United States, Canada and elsewhere have been implemented using LED-based lamps; in addition many existing deployments of incandescent traffic lights are being replaced. Many of the more exotic traffic signals discussed on this page would not be possible to construct without using LED technology. However, color-changing LEDs are in their infancy and may surpass the multi-color array technology.\n\nIn some areas, LED-based signals have been fitted (or retrofitted) with special Fresnel lenses and/or diffusers to limit the line of sight to a single lane. These signals typically have a "projector"-like visibility; and maintain an intentionally limited range of view.
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.
830929
Compact fluorescents are very like ordinary fluorescent bulbs (see refs.) but with smaller, coiled tubes and reduced-size electronic components (starter, ballast) hidden in the base. The price has fallen because of the huge volume they are now made in. They use less power for the light they produce because the light energy is emitted from an ionized gas (and converted to visible light by the phosphor coating inside the bulb) instead of from a heated wire as in conventional light bulbs. This is a more efficient process because it generates far less useless heat, which you can confirm for yourself by feeling one and comparing to the very hot conventional bulb. They also save the consumer more money by having a very long lifetime, typically 10,000-20,000 hours compared to 500-2000 hours for conventional bulbs. Another advantage is that they don't heat the socket they are screwed into nearly as much, resulting in longer socket life too.
931145
I don't know if you're saying they don't last as long as the manufacturer says they should or just that they don't last long, but: the xenon bulbs use a lot of power, about 5 watts compared to the LED's 1 watt. Lithium battery lifetime is given as 2 hours with xenon bulb. See the ref. for the specs.
726469
In a typical 'flashing LED' circuit that uses a capacitor. NORMALLY it will SLOW the frequency of the flash as it takes longer to go through a charge/discharge cycle.\n\nOther circuits that use capacitors for flashing LED can induce a 'decay' in the switch off if using an I.C ('chip') as the timer resulting in the light fading out gradually after each cycle.
1063816
My thinking is...Cars flow through lights in highs and lows. Let's assume during high there are X Cars (each 25ft long) that pass at Y miles/hr. Then the duration for the Green would be:\n\nT = ( [ (25+BD) / 5280)*X] / Y ) * 3600\n\nT=Duration of Green light in secs\nBD=Break Distance in ft\nX= Number of Cars\nY=Speed of the Cars\n\nThere is something missing here...just work on it a little more...\n\nBye
800526
By electrickery of course! Nah basically in layman's terms the electrical energy passing through the gas inside the tube causes the gas to give off photons of light. There is no wire element getting hot and glowing, just gas. Different gas equals different colour light think of "neon lights". Others stuff is also put in along side the gas such as metal elements and often sodium. Street lamps are usually "sodium" bulbs. If you want to find out more use the term "gas discharge lamp" or similar and you'll be more successful in your searches.\n\nthis is worth a look http://en.wikipedia.org/wiki/Gas_discharge
110101
Plants use a very small portion of the light generated by a standard incandescent bulb.  They sell grow lamps which generate a wider spectrum of light that plants can use.
2312
Yes. "A person shall not operate a motor vehicle with a colored transparent or translucent substance or material installed, affixed or applied on or in front of the head lamps, the auxiliary driving lamp or the auxiliary passing lamp or combinations of the head lamps, driving lamp or passing lamp that would obstruct, reduce or interfere with the visibility or effectiveness of the head lamps or that would change the color of light emitted. This paragraph does not prohibit the placement of clear transparent material mounted in front of the head lamps, fog lamps or auxiliary driving lamps."
56171
1.First of all it is cheaper then the standard  lightbulb. I use it all the time instead of the standard filament bulbs that use the wire to heat up. \n\n2. It uses your power (electricity) to move Mercury vapor in argon or neon.\n\n3.  Did you know that that type of light does not stay on steady? It makes many many  blinks too fast for your eye to catch. I tried experimenting with using  a "fan". Only way to fully see the  blinks very well is when it is reaching end of its life.\n\n4. A modified version you could use to grow  plants. But it is not your standard "flourescent" light.\n\nYou could try (likely) to check howstuffworks because if I would explain would run out of space.\n\nWord of caution as always: Never attempt to open one flourescent up it will explode. It will release  Gas and could be more dangerous if you  break it near yourself then a standard  bulb!\n\nI LOVE IT we have brains on Q /A today!  Now  that could be used on the message boards too.
30060
The first automobile traffic light was invented around 1912 by Lester Farnsworth Wire, who was then head of the traffic division of the Salt Lake City Police Department. His two lamps, one red and one green, came from lights then in use on seagoing vessels and railroad signals where they meant stop and go as they do now.\n\nRed has often been the color chosen when the goal was to attract attention, since red, more than any other color, heightens nervous tension in people. Green, on the other hand, has a neutral effect on human emotions, so it was natural to use it to indicate an "okay to proceed" condition. When it was decided to add a caution lamp to the traffic light, yellow was chosen because, other than white, it was the color most distinguishable from red and green. White, of course, was not desired since it could be confused with the many other white lights—such as streetlights—that might be near the traffic light.
176518
Light bulb uses light waves.
683614
On 10 December 1868, the first traffic lights were installed outside the British Houses of Parliament in London. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January 1869, injuring the policeman who was operating it.\n\nThe modern electric traffic light is an American invention. As early as 1912 in Salt Lake City, Utah, policeman Lester Wire set up the first red-green electric traffic lights. On 5 August 1914, the American Traffic Signal Company installed a traffic signal system on the corner of 105th Street and Euclid Avenue in Cleveland, Ohio. Based on the design of James Hoge, it had two colors, red and green, and a buzzer to provide a warning for color changes. The first three-color traffic lights were introduced in New York and Detroit in 1920. In 1923, Garrett Morgan patented a traffic signal device, although it did not directly impact the evolution of the modern traffic light [3].\n\nThe first interconnected traffic signal system was installed in Salt Lake City in 1917, with six connected intersections controlled simultaneously from a manual switch. Automatic control of interconnected traffic lights was introduced March 1922 in Houston, Texas [4]. The first automatic experimental traffic lights in England were deployed in Wolverhampton in 1927. [5]\n\nAmpelmännchen pedestrian traffic signals have come to be seen as a nostalgic sign for the former German Democratic Republic.
982551
Halogens are quite yellow compared to the more modern lights of today(LED, ARC's) so while they may have seemed very bright ten years ago they have just aged a bit but are not any less efficient. You could upgrade the bulb if you want to although it would eat in to your running time.
211837
This is where the general theory of reletivity comes in.  if your car is moving at light speed. it needs a refrence point. Its moving light speed from one point to another point. Say point   A    is the point where you are starting, and point   B  is the point you are going to.  Since YOU are in the car moving at exactly the same speed as the car its general speed is Zero. so the lights would turn on as normal. from a third persons point... say a person on the side of the road point    C    his movement would be ZERO, and YOUR speed would be light speed, as you turn on your headlights they WOULD come on, because once again light speed is general.  Time is general, and space is general.
475042
Incandescent bulbs are yellowish becuase they are not really that efficient in generating white light, they are better at generating heat. The bulb lights up becuase of the heat of light and as it gets hotter it goes through the electromagnetic spectrum: purple-blue to greennish yellow, red-orange and then white. However as incandescents wear out they dont produce white light anymore and produce yellowish light.
998250
Hi again Anna. The best way to explain this is to draw it, but absent that, just imagine a circuit where one "loop" goes to the bulb while the other completes the circuit. In this "parallel" circuit, even if the pathway to the bulb is cut off (as when the bulb blows out), the other loop is still closed, and so the circuit is complete and the circuit is intact.\n\nBut when a series circuit is cut, there is no alternative, loop, pathway. That's it. \n\nImagine driving on a highway and suddenly there is an accident. If you can take the exit and make a detour (a loop around the accident) you can still get to your destination easily. But if that's the only way to your destination, your trip ends there. Having a detour on a highway is like having parallel circuits in electricity.