segunda-feira, 8 de novembro de 2010

Os raios X têm 115 anos





"X-rays were first discovered in 1895 when, during experiments with electric currents passed through a vacuum tube, Wilhelm Conrad Röntgen noted that a nearby fluorescent screen glowed when the current was being passed. When the current was switched off the screen stopped glowing. He attributed this effect to previously unknown rays which, X being the symbol for an unknown quantity, he called X-rays."


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