Electrical Engineering ⇒ Topic : Potential at a Point Due to Group of Point Charges

Potential at a Point Due to Group of Point Charges

Electric potential obeys superposition principle. Therefore, electric potential at any point P due to a group of point charges Q₁,Q₂,Q₃,..........Qn is equal to the algebraic sum of potentials due to Q₁, Q₂, Q₃ ........ Qn at point P. Note that an algebraic sum is one in which sign of the physical quantity (potential in this case) is taken into account. 

                                                        FIGURE (A)

Let the distances of Q₁, Q₂, Q₃, .... Qn  be d₁, d₂, d₃ d_nrespectively from point P as shown in Fig (a) . Further, let V₁, V₂, V₃ V_N be the potentials at P due to Q₁, Q₂, Q₃ .... Q_N respectively. Assuming the medium to be free space/air

If the system of charges is placed in a medium of relative permittivity ε_r, then,