1.14 G AUSS ’ S L AW

. G AUSS ’ S L AW As a simple application of the notion of electric flux, let us consider the total flux through a sphere of radius r , which encloses a point charge q at its centre. Divide the sphere into small area elements, as shown in Fig. . . The flux through an area element Δ S is ˆ φ Δ Δ Δ E S S i i ( . ) where we have used Coulomb’s law for the electric field due to a single charge q . The unit vector ˆ r is along the radius vector from the centre to the area element. Now, since the normal to a sphere at every point is