Page "Electric charge" Paragraph 1

Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter.

There exist two types of electric charges, called positive and negative.

Positively-charged substances are repelled from other positively-charged substances, but attracted to negatively-charged substances ; negatively-charged substances are repelled from negative and attracted to positive.

The SI unit of electric charge is the coulomb ( C ), although in electrical engineering it is also common to use the ampere-hour ( Ah ), and in chemistry it is common to use the elementary charge ( e ) as a unit.

The symbol Q is often used to denote a charge.

The study of how charged substances interact is classical electrodynamics, which is accurate insofar as quantum effects can be ignored.