Search results
Results from the WOW.Com Content Network
The cathode ray tube by which J. J. Thomson demonstrated that cathode rays could be deflected by a magnetic field, and that their negative charge was not a separate phenomenon While supporters of the aetherial theory accepted the possibility that negatively charged particles are produced in Crookes tubes , [ citation needed ] they believed that ...
Cathode ray. A beam of cathode rays in a vacuum tube bent into a circle by a magnetic field generated by a Helmholtz coil. Cathode rays are normally invisible; in this demonstration Teltron tube, enough gas has been left in the tube for the gas atoms to luminesce when struck by the fast-moving electrons. Cathode rays or electron beams (e-beam ...
Thomas Thomson (chemist) Thomas Thomson. Thomas Thomson MD FRS FLS FRSE (12 April 1773 – 2 August 1852) was a Scottish chemist and mineralogist whose writings contributed to the early spread of Dalton's atomic theory. His scientific accomplishments include the invention of the saccharometer [ 1] and he gave silicon its current name.
History of atomic theory. The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.
Plum pudding model. A hypothetical atom with seven electrons, arranged in a pentagonal dipyramid, as imagined by Thomson in 1905. The plum pudding model was the first scientific model of the atom with internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, but it was subsequently ...
The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [1]: 123 Thomson had discovered the electron through his work on cathode rays [2] and between 1897 and 1904 he developed a model for atoms containing electrons arranged in concentric shells.
The Thomson problem is a natural consequence of J. J. Thomson's plum pudding model in the absence of its uniform positive background charge. [ 12 ] "No fact discovered about the atom can be trivial, nor fail to accelerate the progress of physical science, for the greater part of natural philosophy is the outcome of the structure and mechanism ...
The cathode had a concave spherical surface which focused the electrons into a small spot around 1 mm in diameter on the anode, in order to approximate a point source of X-rays, which gave the sharpest radiographs. These cold cathode type X-ray tubes were used until about 1920, when they were superseded by the hot cathode Coolidge X-ray tube.