Introduction

At the end of the nineteenth century several scientists, e.g., Crookes (1879), Julius Plucker (1889), and J.J. Thomson (1896) tried to pass electricity through glasses. They found that electricity can be passed through glasses only when a high voltage is applied at very low pressure. The experiments involving the passage of electricity through glasses at very low pressure were called discharge tube experiments. These experiments showed the emission of certain invisible rays from the cathode. These rays produced fluorescence on glass and affected a photographic plate. These rays were named Cathode Rays. J.J. Thomson studied the properties of these rays in detail which led to the discovery of the electron.

• Cathode rays travel in straight lines away from the cathode.

• Cathode rays are made out of material particles and have kinetic energy..

• Cathode rays get deflected towards the positive electrode when passed through an electric field.

• Cathode rays get deflected from their normal path when they pass through a magnetic field.

• Cathode rays produce fluorescence when they strike the glass wall of the discharge tube.

• Cathode rays produce ionisation in the gas.

• Cathode rays produce X-rays when they strike heavy metal surfaces.

• Cathode rays produce a heating effect.

Number of Electrons in 1 Coulomb of Charge

An electron is a subatomic particle which bears one unit of a negative charge, i.e., ( 1.6021 \times 10^{-19} ) coulombs and has a mass of ( 9.108\times 10^{-28})grams.

Calculation of the number of electrons in 1 coulomb:

q = ne

where, q → Charge, n → no. of e-

e → Charge on e-

1 C = n ( ) ( 1.6 \times 10^{-19} )

n= electrons ( 6 \times 10^{18} )

Conclusion

electrons ( 6 \times 10^{18} ) are present in 1 coulomb of charge.