Electric Charge
Electric charge is a fundamental property of matter. Like charges repel, unlike charges attract. SI unit is the coulomb (C).
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What is electric charge?
Electric charge is a fundamental property of matter that causes it to experience a force in an electric field. There are two types: positive and negative. Like charges repel each other; unlike charges attract. The SI unit of charge is the coulomb (C). The charge on an electron is approximately −1.6 × 10⁻¹⁹ C; the proton has an equal but positive charge.
Conservation of charge
Charge is conserved: the total charge in an isolated system remains constant. Charge can be transferred (e.g. by friction or contact) but not created or destroyed. In circuits, the rate of flow of charge is electric current.
Quantisation of charge
Charge exists in discrete multiples of the elementary charge e ≈ 1.6 × 10⁻¹⁹ C. Any charge Q is an integer multiple of e. This quantisation is important in understanding current at the microscopic level.
If charge is quantised, why does current appear continuous in circuits?