23-08-2015, 09:53 AM
sir is van de graff generator a good topic for seminar
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van de graaff generator ppt file
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sir is van de graff generator a good topic for seminar
10-03-2017, 03:25 PM
A Van de Graaff generator is an electrostatic generator that uses a moving belt to accumulate electrical charge in a hollow metal balloon at the top of an isolated column, creating very high electrical potentials. It produces DC electricity from very high voltage at low current levels. It was invented by American physicist Robert J. Van de Graaff during 1929. The potential difference achieved by the modern generators of Van de Graaff can be as much as 5 megavolts. A desktop version can produce on the order of 100,000 volts and can store enough energy to produce a visible spark. Small machines of Van de Graaff are produced for entertainment, and for the education of physics to teach electrostatics; The largest are shown in some science museums. The Van de Graaff generator was developed as a particle accelerator for physics research, its high potential is used to accelerate subatomic particles at high velocities in an evacuated tube. It was the most powerful type of accelerator of the 1930s until the cyclotron was developed. Van de Graaff generators are still used as accelerators to generate X-ray beams and energetic particles for nuclear medicine research. In order to double the voltage, two generators are often used together, one generating positive and the other negative potential; This is called a Van de Graaff tandem accelerator. For example, the Brookhaven National Tandem Van de Graaff Laboratory reaches about 30 million volts of potential difference. The voltage produced by an outdoor Van de Graaff machine is limited by arc and corona discharge to about 5 megavolts. Most modern industrial machines are enclosed in a pressurized tank of insulating gas; These can reach potentials of up to 25 megavolts.
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