![]() ![]() It can't be air at normal pressure, because that would be too many molecules in the paths of the electrons. That's why the glass tube isn't just a plain vacuum. To have the electron-molecule interactions, of course we need molecules. This is usually much stronger than needed to merely ionize air molecules - we want to those electrons to fly to the anode rather than be scattered by their interactions with the molecules. A stronger field is made by a higher voltage difference applied to the anode and cathode. ![]() How fast they move is determined by the strength of the electric field. Note that the concept of flourescence isn't relevent.įor the electrons emitted by the cathode to do this, they need enough oomph. In a short time, seconds or a fraction of a second, these electrons rejoin the ionized molecules, fall back into the ground states through one or more quantum decays emitting photons. ![]() The negative electrons are pulled strongly enough by the positively charged anode that they whack the electrons in the O2 and N2 molecules, putting them into higher energy states or knocking them free of the molecule. The light emitted from the electron stream comes from nitrogen and oxygen molecules. I know the questions are very silly but because different websites refer to different things, I am becoming confused with something that should be simple to understand. Could someone please tell me why these conditions were necessary? For example, " The cathode rays consist of material particles because they produced shadow of objects placed in the way"ģ.Two of the conditions of the experiment were air at very low pressure and secondly a very high potential difference. The path cathode rays travel is not affected by the position of the anode." I just can't seem to understand this explanation of the one of the observations.Also, different websites analyses this observation differently. That is why, cathode rays cast shadow of any solid object placed in their path. Is this the color of the radiation itself?Ģ." Cathode rays travel in straight lines. However, as shown in the above diagram there was no fluorescent material in the experiment carried out first on the cathode ray tube. Many websites I read through refer to a fluorescent material. The device is called an oscilloscope which is frequently used in medical treatment.1.One of the observations I learned was that the glass tube begins to glow with a brilliant green light. Used to measure changes in electrical voltage with time. They helped the transition from the industrial age to the digital.ģ. Vacuum tubes were initially used in the place of silicon transistors in electronics. In old displays, vacuum tubes were used by directing the beam of electrons using deflection plates, then the beam causes fluorescence on the screen which we see as white.Ģ. So, the cathode ray experiment is also commonly known as J.J. The above modified experiments were performed by J.J. This also helped scientists in finding the charge of electrons. Hence, energy of electron at point A = energy of electron at point B Applying a Magnetic FieldĬathode rays also get deflected from their path if a magnetic field is applied. At point B the electron stops due to the activation of stopping potential, so we apply the law of conservation of energy between the two points. When electrons move from one point to another, say from A to B. When we apply electric field in parallel but in the opposite direction to the cathode rays and if it is sufficiently high for the cathode rays to stop, then the magnitude of the applied voltage is called stopping potential. The magnitude of deviation is proportional to the magnitude of the electric field. When cathode rays hit from the cathode travel towards the anode and hit the anode, a fluorescence or glow is produced.Ĭathode ray deviates from its path due to the application of an electric field. When a high voltage is applied between the two electrodes of an evacuated discharge tube and the back of anode of the discharge tube is coated with a material, like zinc sulfide. They were later named electronsafter particles postulated by George Johnstone Stoney. Thomson measured the weight of cathode rays and showed that they were actually a beam of particles. German scientists Eilhard Wiedemann, Heinrich Hertz and Goldstein said they were some new form of electromagnetic radiation. Scientists Crooks and Arthur Schuster said they were electrically charged atoms. Scientists came up with two theories regarding cathode rays when they were originally discovered. Eugene Goldstein was the one who actually gave cathode rays their name. Cathode rays were first identified by a German physicist named Johann Hittorf when he realized that something was travelling through the tube. ![]()
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