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1895年德国科学家伦琴发现了一种电磁波,就称为X线。X线的波长很短,以光的速度直线前进,肉眼看不见;但迂到一些化合物(如硫化锌镉等),能发出萤光,人就看
In 1895 German scientist Roentgen found an electromagnetic wave, called X ray. The X-ray has a very short wavelength and travels linearly at a light speed that can not be seen by the naked eye. However, some compounds (such as zinc sulfide and cadmium) emit fluorescent light and people look