electric charge

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Property of some bodies that causes them to exert forces on each other. Two bodies both with positive or both with negative charges repel each other, whereas bodies with opposite or ‘unlike’ charges attract each other. Electrons possess a negative charge, and protons an equal positive charge. The SI unit of electric charge is the coulomb (symbol C).

A body can be charged by friction, induction, or chemical change, and the charge shows itself as an accumulation of electrons (negative charge) or a loss of electrons (positive charge) on an atom or body. Atoms generally have zero net charge but can gain electrons to become negative ions or lose them to become positive ions. So-called static electricity, seen in such phenomena as the charging of nylon shirts when they are pulled on or off, or in brushing hair, is in fact the gain or loss of electrons from the surface atoms. A flow of charge (such as electrons through a copper wire) constitutes an electric current; the flow of current is measured in amperes (symbol A).

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