According to Einstein, light of frequency consists of a shower of photons, is of energy . When a photon of light of frequency is incident on a metal, a part of the energy acquired by the electron is used to pull out the electron from the surface of the metal and the rest of it is utilized in imparting K.E. to the emitted electron.
For an arbitrary closed surface, the net outward flow or flux is the product of the average outdrawn normal component of the vector and the area of surface. Electric flux is used to express the relation between and its source. Flux is denoted by
The reason present in a material causes static electricity, electric field in the material and the material become able to attract other materials is called electric charge. It may be positive or negative. Unit of electric charge is coulomb (C).
Optical activity is the ability of a substance to rotate the plane of polarization of plane polarized light. Substances which have this ability are called optically active substance. Tartaric acid is an example of optically active liquid.