Electric Charge

Electric charge is a fundamental property of matter that exists in some of the smallest constituents of substance, and it is the reason electromagnetic force arises between two things. In English it is called "electric charge", in Arabic "الشحنة الكهربائية". It is one of the basic properties of physics, like mass.

Electric charge has two opposite types, commonly designated positive and negative. Objects of like type repel each other, objects of unlike type attract each other. An object with no difference between the two types is called neutral or uncharged.

Origin of charge in matter

The atom consists of a nucleus containing protons (which carry positive charge) and neutrons (which are uncharged), with electrons orbiting the nucleus that carry negative charge. In a normal atom the number of protons and electrons are equal, so overall it is neutral. When an electron leaves or is added to a thing, that thing becomes positively or negatively charged.

The law of conservation

One of the most fundamental laws of physics is that the total charge in an isolated system does not change. Charge cannot be created or destroyed; it can only be transferred from one place to another. For example, when two objects are rubbed together, an electron passes from one to the other, but the total charge remains the same.

Measurement and quanta

In the international system of units (SI), the unit of charge is the coulomb (coulomb), denoted C. Charge is related to electric current, which is the flow of charge over a period of time. Charge breaks down into discrete, inseparable quanta: an elementary charge that electrons and protons possess, and all charge is an integer multiple of this elementary charge.

Force between charges

The force between two stationary charged objects depends on the magnitude of the charges and the distance between them. As distance increases the force decreases rapidly. The concept of an electric field is used to explain how charge influences its surroundings without direct contact.