Discovery of the Electron: J.J. Thomson's Cathode Ray Tube Experiment, Assignments of Earth science

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CATHODE RAY

TUBE

EXPERIMENT

WHAT IS CATHODE RAY

TUBE?

 A cathode-ray tube (CRT) is a vacuum tube in which

an electron beam, deflected by applied electric or

magnetic fields, produces a trace on a fluorescent

screen.

 The function of the cathode ray tube is to convert an

electrical signal into a visual display. Cathode rays or

streams of electron particles are quite easy to

produce, electrons orbit every atom and move from

atom to atom as an electric current

APPARATUS SETUP A Diagram of JJ.Thomson Cathode Ray Tube Experiment showing Electron Beam – A cathode-ray tube (CRT) is a large, sealed glass tube.

The apparatus of the experiment incorporated a tube made of glass containing two pieces of metals at the opposite ends which acted as an electrode. The two metal pieces were connected with an external voltage. The pressure of the gas inside the tube was lowered by evacuating the air.

CONCLUSION

 (^) After completing the experiment J.J. Thomson concluded that rays were and are basically negatively charged particles present or moving around in a set of a positive charge. This theory further helped physicists in understanding the structure of an atom. And the significant observation that he made was that the characteristics of cathode rays or electrons did not depend on the material of electrodes or the nature of the gas present in the cathode ray tube. All in all, form all this we learn that the electrons are in fact the basic constituent of all the atoms.

USES OF CATHODE RAY TUBE  (^) Used as a most popular television (TV) display.  (^) X-rays are produced when fast-moving cathode rays are stopped suddenly.  (^) The screen of a cathode ray oscilloscope, the monitor of a computer, are coated with fluorescent substances. When the cathode rays fall of the screen pictures are visible on the screen.

PLUM PUDDING MODEL

 (^) Thomson’s Plum Pudding Model is given by the English Physicist Sir Joseph John J.J. Thomson. He discovered the electron (first subatomic particle) in the year of 1897. At the time of discovery, J.J. Thomson called this negatively charged particle as corpuscles. Thomson’s Plum Pudding Model is the first model to represent the atomic structure of matter.  (^) According to Thomson’s Plum Pudding Model , a substance is consists of small spheres which are having the radius of about 10- m in diameter. The positive charge is spread uniformly throughout the volume of sphere called pudding. The negatively charged particles Electrons called Plums are distributed as point charges in shells as shown in figure on the next slide: