![]() In 1903, Vanity Fair published a colorful caricature of Crookes, which shows both his splendid beard and mustache, and his tube ( second image). The first image shows a display of original Crookes tubes at the MUMOK, the Museum of Modern Art, in Vienna. We also see two other tubes with Maltese-cross cathodes ( third image), and a view of a worship producing Crookes tubes in 1896 ( fourth image). ![]() ![]() Ashworth, Jr., Consultant for the History of Science, Linda Hall Library and Associate Professor, Department of History, University of Missouri-Kansas City.Sir Joseph John Thomson was a British physicist and Nobel Laureate. He was well-known for the discovery of the electron. In 1897, he showed that cathode rays were composed of very small negatively charged particles. These particles later were named electrons. The apparatus of his experiment is called the cathode-ray tube (CRT). Thomson was not the only one working on cathode rays, but several other players like Julius Plücker, Johann Wilhelm Hittorf, William Crookes, Philipp Lenard had contributed or were busy studying it. However, Thomson's contributions remain more significant than the rest. His experimental results were further investigated by Rutherford and Bohr, which further provided important insights into the atomic world.īefore directly jumping Thomson's findings, let us understand some basic knowledge on cathode rays and the cathode-ray tube. What are cathode rays? Cathode rays are streams of electrons emitted from the cathode (the electrode connected to the negative terminal of a battery). These rays travel in straight lines and can be deflected by electric and magnetic field. The cathode-ray tube (CRT) is a hollow glass tube. Electron emitter (or electron gun): The electron gun comprises of primarily heater and cathode.The air in the tube is pumped out to create a vacuum. It emits the sharp electron beam, cathode rays. In modern CRTs, the electron beam is generated by thermionic emission-using a heating filament-as shown in the above diagram. However, cold-cathode emission mechanism was used in Thomson's experiments. Focusing and accelerating system: It is made up of a series of anodes. ![]() WHICH SCIENTIST PERFORMED THE CATHODE RAY EXPERIMENT SERIES Deflection system: It controls the direction of the electron beam.It will narrow the beam and increase its kinetic energy. This is achieved by an external electric and magnetic field. Phosphorescent coating: It is the final part of the CRT, where the rays strike to create a glow.īack in those days, physicists were unclear whether cathode rays were immaterial like light or were material.Cathode rays bend as they interact with these fields. Many diverse opinions were held on these rays. WHICH SCIENTIST PERFORMED THE CATHODE RAY EXPERIMENT SERIESĪccording to some, the rays are due to some process in the aether. ![]()
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