# Electric charge

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Electric charge is a physical quantity that characterizes the property of objects or particles to interact electromagnetically and determines the magnitude of forces and energies during such interactions.

The unit of electric charge is called the coulomb and is denoted by the letter q.

The movement of electric charges is called electric current.

Electric charges are divided into positive and negative charges.

Positive charge arises, for example, on glass rubbed with paper or silk, while negative charge arises on amber rubbed with wool. Before rubbing, these objects were electrically neutral. When the neutrality of an object is disturbed, it is called charged or electrified.

Bodies with charges of the same sign repel each other, while bodies with charges of opposite signs attract each other.

The process of giving an object an electric charge through the influence of other objects is called electrification.

The process that leads to the appearance of an excess electric charge on bodies or different parts of one body. During electrification, the body gives away or accepts a certain amount of particles with electric charge.

Electrification of objects is accomplished through various methods, the simplest of which is contact. When certain objects come into contact, there is contact between different materials.

During electrification, the existing electric charges are redistributed, and not new charges are created. The law of conservation of electric charge always holds during electrification.

## Law of conservation of electric charge

The total charge of an electrically closed system of bodies remains unchanged during all interactions occurring within this system.

q1, q2, … qn – charges of the bodies that create an electrically closed system

n – the number of such bodies.

An electrically closed system is understood to be a system of bodies into which charged particles from the outside do not penetrate, and which does not lose its “own” charged particles.