In physics, screening is the damping of electric fields caused by the presence of mobile charge carriers. It is an important part of the behavior of charge-carrying fluids, such as ionized gases (classical plasmas), electrolytes, and charge carriers in electronic conductors (semiconductors, metals).In a fluid, with a given permittivity ε, composed of electrically charged constituent particles, each pair of particles (with charges q1 and q2) interact through the Coulomb force as