Electric Charges
Charges are found only associated with the elementary particles of the atom.
Hence Charge can be defined as the property of fundamental particles.
Each atom of any element is neutral with an equal number of electrons(negative charges) and protons (positive charges).
Charging of a body
An object becomes charged when charges are removed from it or added to it. Usually, the charges involved are electrons, as electrons revolve around the outer orbits of the atom, it is easy to remove the electrons. When electrons are removed out of the body, it loses a certain amount of negative charges. Therefore it becomes a positively charged body. When electrons are added, it gains a certain amount of negative charges. It becomes a negatively charged body.
An uncharged body doesn't mean that it doesn't have Charge, but both positive and negative charges are equal in number and hence got neutralised.
There are three methods of charging a body.
1) Charging by friction: When two bodies are rubbed to each other, charges from one body gets transferred to another body. So, one body becomes positively charged, and the other becomes negatively charged.
Example, When a comb is rubbed against the hair, comb becomes charged and attracts the paper pieces.
2) Charging by Conduction: When a charged body comes in contact with an uncharged body, charges from a charged body moves to the uncharged body making it a charged body.
Example, the principle behind the gold-leaf electroscope.
3) Charging by Induction: When a charged body is placed closer to an uncharged body without touching it, charges are induced in the uncharged body to make it charged.
Example, When a charged metal plate is carefully placed parallel to another neutral metal plate.
Properties of Charges
1) Like charges repel each other and unlike charges attract each other.
2) Changes will move in a straight line along the line of unit positive Charge.
3) Force of attraction or repulsion between 2 charges will be determined by columb's law.