in the object and atoms on the surface. Kinetic friction also has similar origin. From these examples, it is clear that understanding electromagnetism is very essential to understand the universe in a holistic manner. The basic principles of electromagnetism are dealt with in volume at XII standard physics.
This unit deals with the behaviour and other related phenomena of charges at rest. This branch of electricity which deals with stationary charges is called Electrostatics. . .
Historical background of electric charges Two millenniums ago, Greeks noticed that amber (a solid, translucent material formed from the resin of a fossilized tree) 12th - 12th - - - - - Unit Electrostatics is another intrinsic and fundamental property of particles. The nature of charges is understood through various experiments performed in the th and th century. The SI unit of charge is coulomb. (ii) Conservation of charges Benjamin Franklin argued that when one object is rubbed with another object, charges get transferred from one to the other.
Before rubbing, both objects are electrically neutral and rubbing simply transfers the charges from one object to the other. (For example, when a glass rod is rubbed against silk cloth, some negative charge are transferred from glass to silk. As a result, the glass rod is positively charged and silk cloth becomes negatively charged). From these observations, he concluded that charges are neither created nor destroyed but can only be transferred from one object to other.
This is called conservation of total charges and is one of the fundamental conservation laws in physics. It is stated more generally in the following way. The total electric charge in the universe is constant and charge can neither be created nor be destroyed. In any physical Following the pioneering work of J.
J. Thomson and E. Rutherford, in the late th century and in the beginning of th century, we now understand that the atom is electrically neutral and is made up of the negatively charged electrons, positively charged protons, and neutrons which have zero charge. The