In polarized materials, the friction between molecules is generated in reaction to the electric field applied and yields an increase in temperature of the material. However, the delay between the penetration of the electric field and the production of heat is called the loss angle δ . The ac electrical conductivity associated with the dielectric loss in the material "σ=ω" "ε" _"0" "ε" ^""" (S/m) is where ω is the angular frequency, 2πf . The loss angle can be expressed as a component of the loss factor as (3)