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Evolution of the Light Bulb

Information found using the sources recommended on the lesson slides
by

Isabella D

on 1 April 2013

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Transcript of Evolution of the Light Bulb

Evolution of the Light Bulb The Original: Incandescents In the 1850's, the demand for energy was much less than it is now in the 21st century. With that increased demand came the necessity of making light bulbs become more efficient so that entire power grids wouldn't collapse. As more efficient bulbs came along, it allowed us to decrease the energy demands for each family (an incandescent can use 525 kWh a year; an LED would use 60 kWh) . Additionally, more efficient bulbs means a decreased impact on our environment, as resources such as coal are needed to produce electricity, so if less electricity needs to produced, it has less of an effect on our Earth. Energy Demands The Original: Incandescents *Pro's: has a nice glow that people like (has a high color rendering index)
*Con's: extremely inefficient: only 10% of the energy is light energy, the other 90% is wasted on heat energy
*Previous problem: it was tough to find a filament that wouldn't melt or "evaporate" (separate from the main body of the filament and cling to the walls of the bulb). Once tungsten was found to be useful, the bulb was also filled with an inert (non-active, full
shell of electrons gas) like argon to keep the
filament from evaporating CFL's: Fluorescent bulbs Presently, these bulbs are what most people use. These bulbs have mercury vapor coating the inside of the glass walls, and when electricity brought through a ballast (a device used to restrict the amount of electrical current being brought in), the atoms of mercury atoms get energized and in turn produce visible light.
*Pro's: they are MUCH more efficient than incandescents, and are very long-lasting
*Con's: they have a low CRI, so the light is harsh-looking. Also, mercury is highly toxic to us, so if the bulb breaks, it could be deadly. They also have to be disposed of in a special way.
*Solutions to these problems: there are steps that your average person can take to clean up a broken cfl to limit the dangers of a broken bulb (such as sealing the broken glass in a plastic bag). Also, there are many organizations that make the proper recycling of the bulbs convenient and safe. Light-Emitting Diodes: LED's These kind of bulbs are relatively new, and are the future of the light bulb. With these bulbs, light is made through "electroluminescence": using a solid (a semiconductor) with positive and negatively charged layers that, when electrical current passes through, the electrons from the negatively-charged side travel through openings to go to the positively charged side of the solid, thus producing light.
*Pro's: They last 10-20 years! They also are capable of emitting nice-looking light, and are 5% more efficient than compact fluorescents.
*Cons: Currently, they are extremely expensive ($100 per bulb) because of the hundreds of little holes in the casings that need to be there to enhance brightness. Also, there isn't a large supply of them, due their newness on the market.
*Solutions to problems: Innovators have found a new way to make those holes in the bulb in a more efficient and less time-consuming way, so the price will decrease. Also, as popularity increases, more bulbs will be produced and the price will fall due to a greater availability of the bulbs. These are the soft-glowing bulbs that showed up in the mid 1800's, courtesy of Edison. The idea with these is that heat produces light. These bulbs have a metal contact at the base of the bulb, have a connecting wire carry electrons up to a coil of tungsten, which energizes atoms and emits light when the temperature of the tungsten gets hot enough. This is because as tungsten atoms get hotter, they become energized and produce light from moving around so much. Sources *http://www.dgpublications.com/blog/2012/01/16/evolution-light-bulb-ppds
*http://home.howstuffworks.com/light-bulb.htm
*http://science.howstuffworks.com/environmental/green-tech/sustainable/cfl-bulb.htm
*http://science.howstuffworks.com/environmental/green-tech/sustainable/led-light-bulb.htm
*http://en.wikipedia.org/wiki/Electrical_ballast
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