charge

Charge is a property of matter that gives rise to electric and magnetic forces and interactions. In physics, electric charge is a conserved quantity carried by elementary particles. Particles with positive charge carry +e, electrons carry -e, where e is the elementary charge equal to approximately 1.602176634×10^-19 coulombs. Objects are electrically neutral when their positive and negative charges balance.

Charges interact through the electromagnetic field. Coulomb's law describes the force between point charges, F = k q1 q2 / r^2, with k the Coulomb constant. In a material medium, charges can move when an electric field is applied, producing an electric current. Conductors transfer charges easily, insulators resist. The net charge in an isolated system is conserved.

Charge can be stored or moved. A capacitor stores charge on conductors separated by a dielectric; charging and discharging involve current flow. The unit of charge is the coulomb; one ampere of current for one second corresponds to one coulomb. The sign of charge determines the direction of the electric field and the flow of current. Common phenomena include ionization, conduction in metals and semiconductors, and plasma behavior. Practical applications include batteries, power supplies, electronic devices, and a broad range of electrostatic techniques.

Other uses of the term charge include a fee for services, an accusation of a crime, or being responsible for a task or duty. These senses derive from the verb to charge, meaning to entrust, assign, or bill.