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The element thallium, discovered by Crookes The mineral crookesite, a selenide of copper, thallium and silver (Cu 7 (Tl, Ag)Se 4), named for Crookes. His first important discovery was that of the element thallium, made with the help of flame spectroscopy. Crookes discovered a previously unknown element with a bright green emission line in its ...
In 1895, the German physicist Wilhelm Conrad Röntgen discovered and extensively studied X-rays, which were later used in X-ray spectroscopy. One year later, in 1896, French physicist Antoine Henri Becquerel discovered radioactivity, and Dutch physicist Pieter Zeeman observed spectral lines being split by a magnetic field.
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight , and constitutes about 10% of the total electromagnetic radiation output from the Sun.
After UV come X-rays, which, like the upper ranges of UV are also ionizing. However, due to their higher energies, X-rays can also interact with matter by means of the Compton effect. Hard X-rays have shorter wavelengths than soft X-rays and as they can pass through many substances with little absorption, they can be used to 'see through ...
1893 – Wilhelm Wien: Wien's displacement law for black-body radiation; 1895 – Wilhelm Röntgen: X-rays; 1896 – Henri Becquerel: Radioactivity; 1896 – Pieter Zeeman: Zeeman effect; 1897 – J. J. Thomson: Electron discovered; 1900 – Max Planck: Formula for black-body radiation – the quanta solution to radiation ultraviolet catastrophe
Maxwell discovered that self-propagating electromagnetic waves would travel through space at a constant speed, which happened to be equal to the previously measured speed of light. From this, Maxwell concluded that light was a form of electromagnetic radiation: he first stated this result in 1862 in On Physical Lines of Force .
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. [1] [2] This includes: electromagnetic radiation consisting of photons, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ)
Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma-ray astronomy. [1] Ultraviolet light is not visible to the human eye. [2]