Question

give a full detail about the discovery of the electron​

Answer 1

Answer:

go through this attachment .....

Answer 2

Answer :

Discovery of Electrons :-

• In 1830, Michael Faraday showed that when electricity is passed through an electrolyte solution, chemical reactions occur at electrodes which results in the liberation and deposition of matter.
• In 1850s, scientist scientist along with Faraday studied electrical discharge in evacuated tubes known as cathode ray discharge tubes.
• It was made of glass, and it contains two pieces of metal called electrodes.
• The electrode is called cathode and the positive electrode is called anode.
• Low pressure is maintained inside the discharge tube.
• A very high voltage is is applied across the electrodes because of which current starts flowing from the cathode to the anode.
• To check of electrons or the flow of current, a hole was made in the cathode and phosphorescent material zinc sulphide was coated at the end of the tube.
• When the cathode rays pass-through anode and strikes the coating of zinc sulphide, a bright spot is developed.
• This tells us that current was flowing from cathode to anode.
• Some results summarised :

1. The cathode rays starts from cathode and moves towards the anode.
2. These are not visible but with the help of fluorescent materials like zinc sulphide we can observe their behaviour.
3. In absence of electrical or magnetic field, these rays travel in straight line whereas in the presence of electrical or magnetic field their behaviour is same as negatively charged particles.
4. The cathode rays consists of negatively charged particles which were then named as electrons.
5. The characteristics of the cathode rays does not depend on the material of electrodes and the nature of gas present in the cathode ray tube.

• In 1897, J.J. Thomson measure the ratio of electrical charge to mass of electron with the help of cathode ray tube.
• He applied magnetic field and electrical field perpendicular to each other to the path of the electrons.
• If the electrical and magnetic field strength is balanced, the electrons travel in a straight line.
• If only magnetic field is applied, the electrons deviate and strike the cathode ray tube at a point below the straight line.
• If only electrical field is applied, electrons deviate and strike the cathode ray tube at a point above the straight line.
• According to him, deviation of the electrons from their path depends on :

1. The magnitude of negative charge on the particle. (Greater - Greater deflection)
2. The mass of the particle. (Lighter - Greater deflection)
3. The strength of the electrical or magnetic field or the voltage across the electrodes. (Greater - Greater deflection)

• The value of ratio of electrical charge to the mass of electron was found to be : 1.758820 × 10¹¹ C/kg.
• R.A. Millikan used a method called oil droplet experiment through which he determine the charge on the electrons.
• The charge on the electrons : -1.6 × 10^{-19} C.
• The results found by J.J. Thomson and R.A. Millikan when combined, helped to determine the mass of the electron : 9.1094 × 10^{-31} kg.