Elektrostatiske

Elektrostatiske, or electrostatics, is the branch of physics that studies electric charges at rest and the forces and fields they produce. It examines how static charges interact, how they distribute on conductors, and how electric potentials arise in systems with fixed charges. The central law for point charges is Coulomb's law: the magnitude of the electrostatic force between two charges q1 and q2 separated by distance r is F = k |q1 q2| / r^2, with k the Coulomb constant. The electric field created by a charge q is defined as E = F/q and represents the force a positive test charge would experience per unit charge; the field direction is the direction of the force on a positive test charge. The superposition principle applies: the net field from several charges is the vector sum of the fields from each charge. Gauss's law sometimes provides a convenient way to link field flux through a closed surface to the enclosed charge: ∮ E·dA = Qenc/ε0. The electric potential V relates to the field by E = -∇V.

In materials, conductors allow free charges to move until equilibrium is reached, yielding stationary surface charges, while insulators (dielectrics) polarize in an external field. The concept of capacitance describes how much charge a system stores at a given potential; for a parallel-plate capacitor, C = ε0εr A/d.

Applications of electrostatics include electrostatic precipitators that remove particles from emissions, electrostatic spray painting and coating, and xerography (electrophotography). Safety considerations include the buildup and sudden discharge of static charges, which can be hazardous in some environments.