This showed that cathode rays consist of negatively charged particles. He observed that cathode rays were deflected towards the positive plate of the electric field. Thomson applied an electric field in the path of cathode rays in the discharge tube. DISCOVERY OF ELECTRONS – THOMSON EXPERIMENT AND RESULT He discovered that cathode rays consist of negatively charged subatomic particles (now called electrons), present in all atoms of the elements. J Thomson discovered electrons while studying characteristics of cathode rays. Although, he could not establish what electric current or cathode rays comprise and what is moving from the negative terminal to the positive terminal.įinally, in 1897 J.
William observed that when he applies a high electric potential across the discharge tube, then current flows from the negative terminal to the positive terminal in the form of rays. William Crooke, the British Scientist, in the year 1875 successfully created a near to perfect vacuum (0.01 mm of mercury) in a glass tube sealed at both ends with metal plates. William Crook is the first person to pass an electric current through a vacuum Thomson tested these ideas by placing negative and positive plates along the sides of the cathode ray tube to see how the. However, most of them failed as none of them were able to create a perfect vacuum.
#Jj thomson cathode ray experiment led to the discovery of series#
After carrying out a series of experiments with – solids, liquids, and gases, scientists took one step further to drive electricity through a vacuum. They proved that the electricity or the electric current can flow through any substance – solid, liquid or gas if enough driving force or electric potential exists. The magnitude of the electric current flowing through a substance is directly proportional to the electric potential applied across it. The electric potential is a driving force that results in the flow of current through a substance due to the difference in concentration of charges at two ends of it. From the results of the experiment, he also postulated that an atom was made up. Scientists in the early nineteenth century were aware of electricity and the effect of electric potential. Thomson was only able to prove the existence of the negatively charged electron. Who discovered electrons CATHODE RAY EXPERIMENT To know about the basic structure of an atom, click here This led to the discovery of the nucleus and other subatomic particles – protons and neutrons. Thomson discovered electrons, the race began among other scientists to uncover the basic structure of an atom. In his quest to study properties of cathode rays, he discovered that atoms contain negatively charged subatomic particles – ‘electrons’. But things changed after the discovery made by an English scientist named J.J. Cathode rays are nothing but a stream of negatively charged particles called electrons. Conclusion: From his experiment, Thomson arrived at the conclusion that. Thomson studied the characteristics and the constituents of cathode rays. Thomson, the one who discovered electronsįor a long period in history, scientists were of opinion that atoms could not be broken further. Hence, these rays are called cathode rays. Thus, we can conclude that electrons area basic constituent of all the atoms.J.
The characteristics of cathode rays (electrons) do not depend upon the material of electrodes and the nature of the gas present in the cathode ray tube.
So the constituents of the discharge tube were negatively charged. By carefully observing the places where fluorescence was observed, it was noted that the deflections were towards the positive side. The air inside the chamber is subjected to high voltage and electricity flows through the air from the negative electrode to positive electrode.Īpparatus is set up by providing a high voltage source and evacuating the air to maintain the low pressure inside the tube.High voltage is passed to the two metal pieces so as to ionize air and make it a conductor of electricity.The electricity starts flowing as the circuit was complete.To identify the constituents of the ray produced by applying a high voltage to the tube, the dipole was set up as an add-on in the experiment.The positive pole and negative pole was kept on the either sides of the discharge ray.When the dipoles were applied, the ray was repelled by negative pole and it was deflected towards positive pole.This was further confirmed by placing phosphorescent substance at the end of discharge ray. Thomson took a tube made of glass containing two pieces of metal as an electrode. It was one of the most important discoveries in the history of physics. Thomson that led to the discovery of the electron. Cathode ray experiment is the experiment performed by J.
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