Electric Potential due to System of Charge—

Let q₁, q₂, q₃ and so on be the charges are placed at the distances r₁, r₂, r₃, and so on respectively from the point P.

Electric Potential—

The Electric Potential at a point in an electric field is defined as the amount of work done per unit positive test charge to bring it from infinity to that point against the electrostatic force due to the Electric Field.

            If V is the electrostatic potential at a point A in the electric field of point charge +q and W is the work done in moving it from infinity to that point against

 the electric force.

Electric Field between Two Plates

Electric Field due to an Infinite Plane sheet of Charge—

Let us consider an infinite thin plate of positive charge having an uniform surface charge density  on both side of the sheet.

Electric field is normal to the plane sheet of charge and directed in outward direction.

Let us assume a cylindrical Gaussian surface of area of cross section ‘A’ through the point P. then,