Question: Obtain an expression for electric field due to an electric dipole at a point equidistant from each charge.
Ans: Let us consider a dipole of charges +q and -q, separated by a distance r. we have to find out the electric field intensity at a point R at equidistance r from P and Q, i.e. to charges. The electric field intensity at point R due to charge +q is given by
E1 = 1/4πϵ0 (q/r2), directed along RU
Similarly, electric field intensity at a point R due to a charge -q at Q is given by E2 in both, magnitude and direction as,E2 = (q/r2), directed along RS
The resultant intensity E in both magnitude and direction is given by diagonal RT of parallelogram RSTU. The resultant intensity id calculated by
E = √ (E12 + 2E1E2 cosθ+ E22)
And direction is given as
Β = tan-1 [E1sinθ/(E2 + E1cosθ)]
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