High-energy electromagnetic radiation with wavelengths shorter than ultraviolet light.X-rays are a form of high-energy electromagnetic radiation with wavelengths shorter than ultraviolet light, typically ranging from about 0.01 to 10 nanometers. They are produced when high-speed electrons collide with matter or when electrons transition between inner atomic shells. X-rays are famous for their ability to penetrate soft tissue but are absorbed by dense materials like bone, making them invaluable in medical imaging and materials science.
X-rays were discovered by Wilhelm Röntgen in 1895, who observed them as an unknown type of radiation that could expose photographic plates. He named them 'X-rays' to signify their mysterious nature, and he received the first Nobel Prize in Physics in 1901 for this discovery.
X-rays are generated when charged particles, usually electrons, are accelerated and then decelerated rapidly, or when they knock inner-shell electrons out of atoms, causing higher-energy electrons to fill the vacancy and emit photons. Because of their short wavelength, X-rays can pass through many materials, but their absorption depends on the atomic number and density of the material. In detectors, X-rays are captured by converting their energy into electrical signals, often using scintillators or semiconductor sensors.
X-rays are used in medical radiography, computed tomography (CT) scans, airport security scanners, and in astronomy to observe high-energy phenomena like black holes and supernovae, as mentioned in the article about invisible light from young galaxies.
X-rays were first used for medical imaging within months of their discovery, and the first X-ray image ever taken was of Röntgen's wife's hand, showing her bones and wedding ring.
