ELECTRIC FLUX THROUGH SURFACE ENCLOSING CHARGE

Lets consider that we have to calculate electric flux of a charge "q" placed inside a spherical body since flux is calculated for a flat body so in order to convert sphere into flat body we will devide the whole sphere into small patches with area ∆A₁, ∆A₂, ∆A₃, ∆A₄----------∆A_n. There corresponding vector areas are parallel to electric field intensity or perpendicular to the surface area as shown in the fig