Flash of the Cathode Rays


Book Description

The electron is fundamental to almost all aspects of modern life, controlling the behavior of atoms and how they bind together to form gases, liquids, and solids. Flash of the Cathode Rays: A History of J.J. Thomson's Electron presents the compelling story of the discovery of the electron and its role as the first subatomic particle in nature. The book traces the evolution of the concept of electrical charge, from the earliest glow discharge studies to the final cathode ray and oil drop experiments of J.J. Thomson and Robert Millikan. It also provides an overview of the history of modern physics up to the advent of the old quantum theory around 1920. Consolidating scholarly material while incorporating new material discovered by the well-respected author, the book covers the continental and English race for the source of the cathode rays, culminating in Thomson's corpuscle in 1897. It explores the events leading to Millikan's unambiguous isolation of the electron and the simultaneous circumstances surrounding the birth of Ernest Rutherford's nuclear atom and the discovery of radioactivity in 1896. The author also focuses on the controversies over N-rays, Becquerel's positive electron, and the famous Ehrenhaft-Millikan dispute over subelectrons. Scholarly yet accessible to those with basic physics knowledge, this book should be of interest to historians of science, professional scientists and engineers, teachers and students of physics, and general readers interested in the development of modern physics.
















CERN.


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German books in print


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NRC Research News


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Low Temperature Physics II / Kältephysik II


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71 For a given value of I the field is independent of the geometrical composition of the coil inside the winding space. The actual number of turns and the cross section of the conductors is entirely determined by the impedance of the power supply to which the magnet should be adapted. In the case of low impedance (high current and low voltage) few turns of thick metal should be used. In the case of high impedance (low current and high voltage) many turns of thin material are needed. High impedance coils are made of square wire or flat strip wound into layers or "pancakes" 1. A nice system for low impedance coils was deve loped by BITTER. The turns of his magnets consist of flat copper discs separated by thin insulating sheets and joined together at their edges. In this type of coil the current density is higher near the axis than at the exterior, resulting into a higher value for G (see above). For the details of the construction we refer to the original papers 2, 3. If the power is dissipated at a low voltage the cooling may be achieved with the help of water. Distilled water should be preferred over mains' water in order to prevent the magnet from corrosion. In the case of a high voltage coil some non-inflammable organic fluid should be used. A low viscosity and a large specific heat are advantageous.