Discovery and History of Cathode Rays
– Cathode rays were discovered by Michael Faraday in 1838.
– Faraday conducted experimental researches in electricity.
– The discovery was published in the Philosophical Transactions of the Royal Society of London.
– The researches were part of Faraday’s series on electrical experiments.
– In the 1870s, William Crookes and others were able to evacuate tubes to lower pressures, leading to the discovery of cathode rays.
– Heinrich Geissler improved the vacuum pump in 1857, observed a glow in the tube when a high voltage was applied.
Properties of Cathode Rays
– Cathode rays are emitted by the negative electrode, or cathode, in a vacuum tube.
– Cathode rays consist of a previously unknown negatively charged particle, later named the electron.
– Cathode rays can be deflected by electric and magnetic fields.
– Cathode rays can cause fluorescence when they strike the glass wall of the tube.
– Cathode rays travel in straight lines and produce shadows when obstructed by objects.
Applications and Uses of Cathode Rays
– Cathode-ray tubes (CRTs) use focused beams of electrons deflected by electric or magnetic fields to create images.
– CRTs are used in televisions, computer monitors, oscilloscopes, and electron microscopes.
– Electron microscopes utilize cathode rays to magnify and analyze small objects with high resolution.
– Cathode rays carry electric current through the tube, allowing for the transmission of signals and information.
– Vacuum tubes, based on the principle of controlling cathode rays, were used in early electronic amplification devices.
Cathode Rays and Quantum Physics
– J.J. Thomson conducted experiments on cathode rays and measured their mass, showing they were particles.
– C. Davisson and L. Germer demonstrated the diffraction of electrons by a crystal of nickel.
– G.P. Thomson and A. Reid observed the diffraction of cathode rays by a thin film.
– These experiments provided evidence for the wave-like nature of cathode rays.
– Cathode rays played a significant role in the development of quantum physics.
Influence and Significance of Cathode Rays
– The discovery of cathode rays paved the way for the development of television.
– Cathode ray tubes (CRTs) were used in early television sets, oscilloscopes, and computer monitors.
– The study of cathode rays contributed to the understanding of atomic structure.
– Cathode rays sparked interest in the field of quantum physics and led to significant contributions by scientists.
– Cathode rays continue to be studied and have applications in various scientific fields. Source: https://en.wikipedia.org/wiki/Electron_beam
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Cathode rays or electron beams (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to electrons emitted from the cathode (the electrode connected to the negative terminal of the voltage supply). They were first observed in 1859 by German physicist Julius Plücker and Johann Wilhelm Hittorf, and were named in 1876 by Eugen Goldstein Kathodenstrahlen, or cathode rays. In 1897, British physicist J. J. Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, which was later named the electron. Cathode-ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to render an image on a screen.
