Electrostatic

Electrostatic refers to electric phenomena associated with stationary or slowly varying electric charges. In physics, electrostatics studies the forces, fields, and potentials produced by charges at rest or moving sufficiently slowly that radiation can be neglected. The subject is foundational to classical electromagnetism and underpins many technological processes and devices.

Coulomb's law describes the force between point charges: F = k q1 q2 / r^2, directed along the line joining the charges. The electric field E represents the force per unit charge, E = F/q, and the electric potential V relates to work done in moving a test charge. Gauss's law and the concept of capacitance extend these ideas to extended charge distributions and circuits.

Key phenomena include electrostatic induction, where a conductor develops surface charges in response to external charges; charge conservation; and shielding, such as Faraday cages that block external static fields. Dielectric materials affect electric fields by polarizing in response to applied fields, altering capacitance and field distribution.

Applications span environmental, industrial, and imaging technologies. Electrostatic precipitators remove particles from exhaust streams; spray painting and powder coating rely on charged particles and opposing surfaces to improve deposition; xerography and laser printers use latent electrostatic images; capacitors and high-voltage components exploit stored electrostatic energy.

In practice, electrostatics requires attention to safety and air breakdown. Very strong fields can ionize air, producing corona discharge or arcing. Common quantities are the coulomb, volt, farad, and newton; the field is measured in volts per meter. The domain complements magnetostatics within the broader theory of electromagnetism.