Cathode rays.

In the end of nineteenth century, the ca scientists were quite comfortable with the ca concept of atom and knew a good deal about su their relative masses and properties, while many ca physicists and chemists decided physical op existence of the atom. During the nineteenth in century, several discoveries were made in the O field of physics which prevail the physical pe existence and the structure of an atom. This be part of story begins with the study of cathode fo rays. We are using cathode rays almost every sh day, we may not be aware of it. The heart of a au television set and its picture tube is a cathode m rays tube. Johann Hittorf was the first scientist to observe by cathode rays. In his paper published in 1869, he th described in detail what happens when high as voltage is placed across two electrodes, sealed in cl a glass tube, connected to a vacuum pump. As u the air is pumped out of the tube, a colourful glow first appears in the glass near the cathode- r the negative electrode. As the gas pressure in 1 the tube is reduced, the glow spreads through e online volume between the two electrodes the tube is reduced, the glow spreads through the entire volume between the two electrodes. The colour of this glow discharged depends on the kind of gas originally in the tube. As the tube is evacuated to still lower pressure, the glow discharge disappears. A dark region starts to form near the cathode and then moves across the tube towards the anode, the positive electrode, as the pressure is further reduced When the dark region has moved completely across the tube, a new phenomenon appears. Instead of the gas glowing, there is now a faint glow on the glass wall of the tube opposite thecathode. Since the darkness begins near the e cathode and spreads across the tube. Scientists ut summarized that something emitted from the y cathode vias responsible for the glow on the al opposite wall of the tube. For this reason, the th invisible radiation was called Cathode Rays. he One of the simple experiments, that can be al performed with cathode rays, is reflecting the his beam with a magnet. If cathode rays are de focused into a narrow beam by appropriate ry shaping and positioning of the cathode and f a anode, the beam can be moved around with a de magnet. If the north pole of magnet is brought down from the top, the spot of the light created ve by the beam is deflected to the left on the face of he the tube. This result is consistent with the gh assumption that the cathode rays are negatively in charged particles which we can confirm by As using the right hand rule for the negative forces The questions about the nature of cathode de rays were largely explained by J.J. Thomson in in 1891. Thomson performed a series of zh experiments to measure the masses of the es negatively charged particles. experiment, he passed the beam through crossed electric and negative fields of known strength. The combined effect of the electric and magnetic field on the beam allowed him to estimate the velocity of the particles, since the magnetic force depends on velocity, but the electric force does not. Knowing the velocity and the extent of deflection produced by the magnetic field alone, he could estimate the mass of particles. By Newton’s Second Law of Motion, the acceleration of the particles by themagnetic field that crosses their deflection, is inversely proportional to their mass As, the magnetic force also depends on the charge of the particles which was not known. JJ Thomson actually ended up measuring the ratio of the charge of mass. He published the results of this work in 1897. The striking features of Thomson’s result were apparently the small mass of the particles and fact that all of them remained to have the same ratio of charge to mass, which suggested that the particles were identical. The lightest element of the periodic table is Hydrogen. If Hydrogen ion and cathode rays particles had the same charge, the mass of the Hydrogen atom was nearly 2000 times larger than the mass of cathode rays particles. Not only were these particles identical for a given cathode they had the same charge to mass ratioeven if the cathode was made of different metal Thomson checked this result by repeating the experiment with cathode was made of different metals. The same particles seemed to be present all those that he tested. This fact together with their small mass suggested that these particles must be common constituents of different types of atoms. Now we call negatively charged particle of the cathode rays beam electrons and Thomson is credited with discovering electron in these experiments A cathode ray beam is a beam of electrons Each electron is now known to have a mass of 9.11 10 Kg. Thomson’s discovery provided the ti known substance particle, a particle smalle than the smallest known atom. The electron became the first possible candidate for d building block of atoms

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Asim mahesar
I am a hobbyist web developer, designer & Internet Marketer. I am also a Penetration Tester. I've spent the great part of two decades working as a developer and user experience designer. Apart from development I love to do marketing whether its a SEO or pure internet marketing. I fallen in love with security in 2011, now its my hobby to learn about security and find vulnerabilities but in a ethical way.


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