Potential Energy of an Electric Dipole, when placed in Uniform Electric Field--

Let us consider an Electric Dipole having dipole moment p is placed making an angle θ with external field . Then torque acting on the dipole is given by,

Electric potential Energy of a System of Charge—

The Electric Potential Energy of a system of point charges is defined as the work required to bring the charges constituting the system to their respective position from infinity.

Let we have three point charges q₁, q₂ and q₃ which are initially placed at infinity.

To bring the charge q₁ from infinity to its position, no work is Required.

When q₂ is brought to its position B, q₁ is already present,

Equipotential surface—

Any surface which has same electric potential at every point is called an equipotential surface

Electric Potential due to a Point Charge—

Let us consider a point charge +q placed at point O.

Suppose that at any instant q₀ is at P at the distance‘r’ from ‘O’. If E be the electric field intensity at P. then,