1. GROUP PROJECT How light bulb works Qianmeng Gu qxg5019 Linnan Zhang lqz5068 Ying Ye yoy5069

2. Light bulbs are very common in our daily life and is probably one of the most significant inventions in science. The light bulbs is used in various fields such as communication and sports.

3. The inventor Thomas Alva Edison (in the USA) experimented with thousands of different filaments to find just the right materials to glow well and be long-lasting. In 1879, Edison discovered that a carbon filament in an oxygen- free bulb glowed but did not burn up for 40 hours. Edison eventually produced a bulb that could glow for over 1500 hours. History of light bulbs

4. Light bulbs have a very simple structure. At the base, they have two metal contacts, which connect to the ends of an electrical circuit.electrical The metal contacts are attached to two stiff wires, which are attached to a thin metal filament. The filament sits in the middle of the bulb, held up by a glass mount. The wires and the filament are housed in a glass bulb, which is filled with an inert gas, such as argon.

5. The physics aspect ---How light bulbs work 1.Tungsten filament, a thread metal plays a important role in lighting the bulb. It has a property of a resistant. Resistance is the amount of friction that an object will put against electricity flowing through it. 2.Electricity flows through the filament in the light bulb, making it white-hot and the light bulb starts glowing as filament has a lot of resistance to electricity, converting electrical energy to light and heat energy. 3.Conversion of heat energy can be explained by the Joule-effect, which means that resistances heat up when electrical current runs through them.

6. CONTRIBUTION OF LIGHT BULBS The invention of light bulbs has changed the world by including but not limited to letting people do work at night. Travel: night travels by automobiles, light guidance for all transportations such as ships and airplanes Medicine: All internal and non-intrusive medical procedures use variants of the original light bulb. Mining: provide a safer and healthier environment for miners by eliminating breathing difficulties War: eliminate the risk of being bombed by surprise

7. DIFFERENT TYPES OF LIGHT BULBS LEDs: glows when electricity passes through them Halogen lamps: similar to incandescent lamps Sodium vapor lamps: similar to fluorescent lamps, except that their light is already all in the visible range Mercury vapor lamps: similar to fluorescent light bulbs, except that they are brighter

9. NEW INSIGHTS Modern light bulbs don't hold a vacuum. Instead they are filled with an inert (electrically non-conducting) gas such as Nitrogen There are more options of light bulbs available in the market Starting on January 12, 2012, the Energy and Independence and Security Act of 2007 (EISA) began regulating energy- efficiency standards for 100-watt screw-in light bulbs (also known as Edison or A19 lamps). Considering energy efficiency, LED have improved rapidly in the last couple of years and there are now several bulbs that meet Energy star criteria

10. WORKS CITED (N.D.). RETRIEVED 04 12, 2012, FROM HTTP://EN.WIKIPEDIA.ORG /WIKI/INCANDESCENT_LI GHT_BULB LIGHTBULBCHOIC.COM. (2011, 12 23). RETRIEVED 04 12, 2012, FROM TRADITIONAL LIGHT BULBS NOT GOING AWAY… YET: HTTP://LIGHTBULBCHOICE.COM/NEWS/2011/12/TRADI TIONAL-LIGHT-BULBS-NOT- GOING-AWAY-YET/ ANSWERS.COM. (N.D.). RETRIEVED 04 12, 2012, FROM HOW DOES A LIGHT BULB WORK?: HTTP://WIKI.ANSWERS.CO M/Q/HOW_DOES_A_LIGHT _BULB_WORK HARRIS, T. (N.D.). HOW STUFFS WORK. RETRIEVED 4 12, 2012, FROM HOW LIGHT BULBS WORK: HTTP://HOME.HOWSTUFFW ORKS.COM/LIGHT- BULB1.HTM WORKS CITED (n.d.). Retrieved 04 12, 2012, from http://en.wikipedia.org/wiki/Incandescent_light_bulb LightBulbChoic.Com. (2011, 12 23). Retrieved 04 12, 2012, from Traditional light bulbs not going away… yet: http://lightbulbchoice.com/news/2011/12/traditional-light-bulbs-not- going-away-yet/ Answers.com. (n.d.). Retrieved 04 12, 2012, from How does a light bulb work?: http://wiki.answers.com/Q/How_does_a_light_bulb_work Harris, T. (n.d.). How stuffs work. Retrieved 4 12, 2012, from How Light Bulbs Work: http://home.howstuffworks.com/light-bulb1.htm

11. Thank you for your attention