What is an Electric Charge?
The electric charge is a property of subatomic particles (protons and electrons), which determines their electromagnetic interaction. The proton has a charge of e and the electron has a charge of -e. An electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. The SI unit of electric charge is the coulomb (C), although in electrical engineering it is also common to use the ampere-hour (Ah). An electric charge can either be positive or negative. Two positively charged substances will repel each other. So will two negatively charged objects. A positively charged object and negatively charged object will attract each other. The study of how charged substances interact is called classical electrodynamics.
Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force.