2025年1月26日 · Plasma, in physics, an electrically conducting medium in which there are roughly equal numbers of positively and negatively charged particles, produced when the atoms in a gas become ionized. It is sometimes referred to as the fourth state of matter, distinct from the solid, liquid, and gaseous states.

Sir William Crookes (born June 17, 1832, London, Eng.—died April 4, 1919, London) was a British chemist and physicist noted for his discovery of the element thallium and for his cathode-ray studies, fundamental in the development of atomic physics.. After studying at the Royal College of Chemistry, London, Crookes became superintendent of …

2024年12月11日 · Atom - Kinetic Theory, Gases, Particles: Whereas Avogadro’s theory of diatomic molecules was ignored for 50 years, the kinetic theory of gases was rejected for more than a century. The kinetic theory relates the independent motion of molecules to the mechanical and thermal properties of gases—namely, their pressure, volume, temperature ...

2025年1月6日 · Niels Bohr proposed a model of the atom in which the electron was able to occupy only certain orbits around the nucleus. This atomic model was the first to use quantum theory, in that the electrons were limited to specific orbits around the nucleus.

2025年2月5日 · The Rutherford model supplanted the “plum-pudding” atomic model of English physicist Sir J.J. Thomson, in which the electrons were embedded in a positively charged atom like plums in a pudding. Based wholly on classical physics , the Rutherford model itself was superseded in a few years by the Bohr atomic model , which incorporated some ...

2025年1月26日 · Analogously, just as buoyancy effects guide water waves, plasma oscillations are related to waves in the electron component of the plasma called Langmuir waves. Wavelike phenomena play a critical role in the behaviour of plasmas.

2025年1月30日 · The result is an ionized gas consisting of free negative electrons and positive nuclei. This ionized gas is in a plasma state, the fourth state of matter. Most of the matter in the universe is in the plasma state. At the core of experimental fusion reactors is a …

2025年1月31日 · In nuclear fission the nucleus of an atom breaks up into two lighter nuclei. The process may take place spontaneously in some cases or may be induced by the excitation of the nucleus with a variety of particles (e.g., neutrons, protons , deuterons , or alpha particles) or with electromagnetic radiation in the form of gamma rays .

2024年12月21日 · Eugen Goldstein was a German physicist known for his work on electrical phenomena in gases and on cathode rays; he is also credited with discovering canal rays. Goldstein studied at the University of Breslau (now in Wrocław, Pol.), where he received his doctorate in 1881. His career was spent at

Thomson atomic model, earliest theoretical description of the inner structure of atoms, proposed about 1900 by William Thomson (Lord Kelvin) and strongly supported by Sir Joseph John Thomson, who had discovered (1897) the electron, a negatively charged part of every atom.