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Since people understood how to use fire, people have also developed many products to catch light. Now, we can protect ourselves from being in the dark by using them... |
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1. Light Bulb Incandescent Lamp Sit at the desk, turn on light bulbs. Do you ever think about it, light bulbs? Let's see a light bulb. When electricity passes into the bulb, it go through that filament. The resistance of the conduct brought it to incandescence. In the end, the bulb failure because the vaporization of the filament make the bulb no circuit. As to the filament in the vacuum bulb, there are many experiments doing by many people. At first, some people ever use carbonized strip, or bamboo. In the twentieth century, people use a tungsten filament in almost vacuum bulb. |
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| 2. Fluorescent Lamp We often use fluorescent lamp in many places, because of its less cost and longer time of use. Inside the tube, we paint a fluorescent powder. In the tube, we pour mercury vapor into the tube. In two ends, there are base pins. These two electrodes alternately serve as a anode or a cathode. In the side of a cathode, the coil emits many electrons, which collide mercury atoms. Mercury atoms are in the excited state. When mercury atoms return to ground state, they let off energy most in the form of ultraviolet radiation. Fluorescent powder change ultraviolet radiation to visible light. Fluorescent lamps have a auxiliary equipment, which is named a ballast. It can provide a proper voltage and current. Picture 2 looks like a small bucket. It is a starter which makes a fluorescent lamp work. You can see picture 2.^_^ I am not discouraged, because every
wrong attempt discarded is another step forward. |
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