![]() Now, he put a negatively charged metal plate on one side of the cathode rays to go past the anode, and a positively charged metal plate on the other side. Then he conducted a Second experiment, to prove the charge carried by the cathode rays was negative or positive. From this, he deduced that the electric charge and the cathode rays must be combined and are the same entity. From the first experiment, he discovered that the electrometers stopped measuring electric charge. The metal had two small diversions(slits), leading to an electrometer that could measure a small electric charge. ![]() He built his cathode ray tube with a metal cylinder on the other end. Thompson, conducted his first cathode ray tube experiment to prove that rays emitted from an electron gun are inseparable from the latent charge. Screen: - The inner layer of the screen is coated with phosphorus, and produces fluorescence when cathode rays hit the screen by a process of phosphorus excitation.Īquadag: - It is an aqueous solution of graphite used to collect the secondary emitted electrons which are required to keep the cathode ray in electrical equilibrium. The electron gun has a heater, cathode, pre-accelerating anode, focusing anode and accelerating anode.ĭeflecting Plates: - They produce a uniform electrostatic field only in one direction, and accelerate particles in only one direction. A wire is connected from anode to cathode to complete the electrical circuit.Įlectron Gun Assembly: - It is the source of the electron beams. When a potential difference is applied, the electrons jump to an excited state and travel at high speeds to jump back-and-forth inside the vacuum glass chamber and when some cathode rays certain molecules of the cathode screen, they emit light energy. Since electrons are repelled by the negative electrode, the cathode is the source of cathode rays inside a vacuum environment. The cathode is a negative electrode, Anode is the positive electrode. To illustrate the effects of an electric field on a charged particle.Cathode rays are a beam of negatively charged electrons traveling from the negative end of an electrode to the positive end within a vacuum, across a potential difference between the electrodes.To commemorate the discovery of the electron by J.As a result of his work, Thomson proposed a completely new model of the atom (Thomson’s Plum Pudding Model) that one of his students, Ernest Rutherford, would improve upon 10 years later.Ĭlick and drag the cursor to change the intensity of the voltage applied between the plates. This apparatus constitutes the first particle accelerator. Thomson, in 1897, isolated a new elementary particle carrying a negative charge – the electron. The very intense electric field that results from this accelerates the few ions present in the tube which, via collisions, ionize other particles. The lower the pressure, the more the electrons thus liberated and accelerated travel great distances until they strike the screen at the opposite end of the tube.īy studying the deviation of this beam, J. A high voltage (between 10 and 100 kV) is applied between two electrodes. Thomson’s second experiment involving the deviation of an electron beam in a vacuum tube, called a Crookes Tube.Ī partial vacuum (less than 10 -6 atm) is maintained in the tube.
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