CBSE Class 12-science Answered

Electric potential V at a point due to point charge q is 

V = K * (q /d )

where K = 1/(4πε_o ) = 9 × 10⁹ N m² C^-2 is Coulomb's constant .

Potential is scalar quantity. Net potential due to multiple charges are sum of potential of individual charges.

Hence in the given charge configuration of two point charges +0.12 μC and -0.06 μC ,

potential at mid point P between two charges is

V = 360 V

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Workdone to bring a 0.2 μC charge from infinity to the point P equals to potential energy of 0.2 μC at point P.

Potential energy of charge q at a point P is (q V ) where V is potential at that point.

Workdone to bring a 0.2 μC charge from infinity to the point P = 0.2 × 10^-6 × 360 J = 7.2 ×10^-5 J