Electromagnetic radiation of extremely short wavelength (100 nanometres to 0.001 nanometre) produced by the deceleration of charged particles or the transitions of electron s in atoms.
X rays travel at the speed of light and exhibit phenomena associated with wave s, but experiments indicate that they can also behave like particles (see wave-particle duality ). On the electromagnetic spectrum , they lie between gamma ray s and ultraviolet radiation . They were discovered in 1895 by Wilhelm Conrad Röntgen , who named them X rays for their unknown nature. They are used in medicine to diagnose bone fractures, dental cavities, and cancer; to locate foreign objects in the body; and to stop the spread of malignant tumours. In industry, they are used to analyze and detect flaws in structures.