A light bulb has an efficiency of 10%. A 40 watt light bulb gives off 4 watts of light. That leaves 36 watts of heat. Now you can look up the formula to get the conversion factor to joules so you can get the right answer for your homework.
http://wiki.answers.com/Q/How_much_heat_does_a_40w_bulb...
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That is why manufacturers put actual light output ratings (in lumens) on compact fluorescent light bulbs, as well as a comparison (for example "produces as much light as a 60W incandescent light bulb"). Bulbs of different types but the same wattage would produce different amounts of heat.
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www.newton.dep.anl.gov/askasci/eng99/eng99475.htm
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Incandescent lights give off heat as well as light energy. The higher the wattage of the light bulb the higher the temperature. A compact fluorescent bulb gives off very little heat energy because they do not use resistance and cause a light to glow hot.
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www.energyquest.ca.gov/projects/heat.html
www.energyquest.ca.gov/projects/heat.html
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In experiment B you will, using a light bulb, convert electrical energy into heat from which you will determine Joule's constant again for this process. ... These two parts exert frictional forces on each other which generate heat. ... 12. Remove the thermometer from the jar. Note how much of the thermometer is immersed in the water.
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teacher.nsrl.rochester.edu/phy_labs/Heat/Heat.html
teacher.nsrl.rochester.edu/phy_labs/Heat/Heat.html
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In fact, most of the energy that goes into incandescent light bulbs results in heat. Very little of the energy ends ... It is very much less inefficient for a fluorescent bulb. That is why a 15W fluorescent bulb is roughly about as bright as a 100W incandescent bulb. More of the 15W goes into light in the fluorescent bulb.
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www.madsci.org/posts/archives/mar99/920989031.Ph.r.html
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How much heat (or infrared radiation) is emitted by regular, halogen, and compact fluorescent light bulbs?; Regular light bulbs, known as incandescent bulbs, create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see.
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www.gelighting.com/na/home_lighting/ask_us/faq_compact....
www.gelighting.com/na/home_lighting/ask_us/faq_compact.htm
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Tungsten-filament bulbs — the most widely used light source in the world — burn hands if unscrewed while lit. The bulbs are infamous for generating more heat than light. ... Would the structure melt through the buildup of heat? Or, more desirably, would the thermally excited tungsten atoms ... New Light Bulb...
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www.sciencedaily.com/releases/2002/05/020509074556.htm
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Incandescent light bulb - Wikipedia, the free encyclopedia
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The incandescent light bulb , incandescent lamp or incandescent light globe is a source of electric light that works by incandescence (a general term for heat-driven light emissions which includ...
en.wikipedia.org/wiki/Incandescent_light_bulb
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They are wasteful: 95 percent of the power used by incandescents is given off as heat. This is why an Easy-Bake Oven can make a cookie using a light bulb. ... fluorescent technology has been deployed commercially since the 1930s. Today's CFLs use about one-third as much power as incandescents, to produce the same amount...
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money.cnn.com/2007/02/13/magazines/fortune/gunther_plug...
money.cnn.com/2007/02/13/magazines/fortune/gunther_pluggedin_lightbulb.fortune/index.htm
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