Elektrostatia

Electrostatia, or electrostatics, is the branch of physics that studies electric charges at rest or moving slowly and the electric fields and forces they produce. It covers how charges distribute themselves on conductors, how electric fields propagate through space, and how different materials respond to electric fields.

The core principles include Coulomb’s law, which states that the force between two point charges is proportional to the product of their charges and inversely proportional to the square of the distance between them. This leads to the concept of an electric field, defined as the force per unit charge acting on a small test charge. The electric potential describes the work needed to move a charge within the field. In many problems, Maxwell’s equations for the electrostatic limit apply, including Gauss’s law, which relates the electric flux through a closed surface to the enclosed charge.

A central object in electrostatics is the capacitor, which stores energy in the electric field created by separated charges. The capacitance, C, depends on geometry and materials (C = εA/d for a parallel-plate capacitor), and the stored energy is U = 1/2 CV^2. Dielectrics affect field strength and energy storage by reducing the effective field within the material.

Applications of electrostatics are widespread. Capacitors and dielectric materials are fundamental in electronics. Electrostatic precipitators remove particles from gas streams, xerography (electrophotography) uses charged particles to form images, and electrostatic painting and spray deposition apply charged droplets to achieve uniform coats. Static electricity and triboelectric effects explain shocks and appliance wiring phenomena when charged objects come into contact and separate.

Historically, Coulomb quantified the force between charges in the 18th century, laying the foundation for electrostatics, with later developments expanding the understanding of electric fields and their interactions.