Two point charges `q_1 and q_2` of magnitude `+10^(-8) C and -10^(-8) C ` respectively are placed 0.1 m apart . Calculate the electric field at point B ,C and A
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Explanation

Given charges ` q_1 and q_2 ` constitute an electric dipole of dipole moment ` p=q 2a =10 ^(-8) xx 0.1 = 10 ^(-9) C -m `
(i) Point B lies on the axial line of dipole, where ` " " r= 0.05 + 0.05 =0.1 m , `hence
` E_B =(1)/( 4 pi in _0) .(2pr)/( (r^(2) -a^(2)) ^(2)) `
` " " ( 9xx 10^(9) xx 2 xx 10^(-9) xx 0.1 )/([(0.1)^(2) -(0.05) ^(2) ]^(2)) =3.2 xx 10 ^(4) N//C `directed along NM.
(ii) Point C lies on the equatorial line of dipole ,where ` sqrt ( a^(2) +r^(2)) = 0.1 m, ` hence
` therefore E_C =(1)/( 4 pi in _0) . (p)/( (a^(2) +r^(2)) ^(3//2)) =(9xx 10^(9) xx 10 ^(9)) /( (0.1)^(3)) = 9xx 10 ^(3) N//C ` along MN.
(iii) Point A also lies at equatorial line where r=0
`therefore " "E_A=(1)/( 4 pi in _0) .(p)/(a^(3)) =(9xx 10^(9) xx 10 ^(-9))/((0.05)^(3)) =7.2 xx 10 ^(4) N//C ` along MN.