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Electron gas can undergo plasma oscillation, which is waves caused by synchronized variations in electron density, and these produce energy emissions that can be detected by using radio telescopes. [165] The frequency of a photon is proportional to its energy. As a bound electron transitions between different energy levels of an atom, it ...
The electron neutrino was simply called the neutrino, as it was not yet known that neutrinos came in different flavours (or different "generations"). Nearly 40 years after the discovery of the electron, the muon was discovered by Carl D. Anderson in 1936. Due to its mass, it was initially categorized as a meson rather than a lepton. [26]
This became the classic means of measuring the charge-to-mass ratio of the electron. Later in 1899 he measured the charge of the electron to be of 6.8 × 10 −10 esu. [32] Thomson believed that the corpuscles emerged from the atoms of the trace gas inside his cathode-ray tubes. He thus concluded that atoms were divisible, and that the ...
1932 Antielectron (or positron), the first antiparticle, discovered by Carl D. Anderson [13] (proposed by Paul Dirac in 1927 and by Ettore Majorana in 1928) : 1937 Muon (or mu lepton) discovered by Seth Neddermeyer, Carl D. Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays [14] (it was mistaken for the pion until 1947 [15])
In 1897, J. J. Thomson discovered the electron using the cathode-ray tube. In 1898, Wilhelm Wien demonstrated that canal rays (streams of positive ions) can be deflected by magnetic fields and that the amount of deflection is proportional to the mass-to-charge ratio .
An image from John Dalton's A New System of Chemical Philosophy, the first modern explanation of atomic theory.. This timeline of chemistry lists important works, discoveries, ideas, inventions, and experiments that significantly changed humanity's understanding of the modern science known as chemistry, defined as the scientific study of the composition of matter and of its interactions.
J. J. Thomson (1856–1940) discovered the electron and isotopy and also invented the mass spectrometer. He was awarded the Nobel Prize in Physics in 1906. In the 19th century, experimenters began to detect unexpected forms of radiation: Wilhelm Röntgen caused a sensation with his discovery of X-rays in 1895; in 1896 Henri Becquerel discovered ...
Perey discovered it as a decay product of 227 Ac. [178] Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [179]