Thursday, May 10, 2007

On This Day

By Princessa

After noticing that a sharp needle would conduct electricity away from a charged metal sphere, Benjamin Franklin began experimenting with lightning rods. A lightning rod is thick metal rod in use, Franklin's were pointed at the top. It was his belief that the pointed rod attracted the lightning more effectively and conducted the electrical charge more efficiently into the ground. Franklin's first test took place in May of 1752, but he went on to conduct many others. He wanted to prove conclusively that lightning was electricity. In June he and his son attached aextending into the air and embedded into the earth. Its purpose is to attract lightning and conduct it safely away from buildings and into the ground. In contrast to lightning rods already kite with a metal key hanging from it to a church steeple that would act as a lightning rod. As the kite flew in the storm, he noticed that the hairs on the string leading to it were standing up and concluded that this was due to static electricity. The following September he used a lightning rod he had installed in his own house for another experiment. He fastened two bells to it that would ring when the rod was electrified. Unexpectedly they rang even at times when there was no detectable lightning. The pointed shape of Franklin's rods actually became part of the political dispute between England and its colonies in America. In England rounded lightning rods were in use, and, because of Franklin's association with the colonial struggle for independence, the English refused to use pointed rods - even though their own scientists' experiments indicated that rounded rods increased the likelihood of electrical explosions. The Americans, on the other hand, installed pointed rods on their public buildings not only for the sake of safety but also to make a political statement.

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