Six charges are placed at the vertices of a rectangular hexagon as shown in the figure. The electric field on the line passing through point O and perpendicular to the plane of the figure as a function of distance x from point O is (xgtgta)

Explanation

This is basically a problem of finding the electric field due to three dipoles. The dipole moment of each dipole is `P=Q(2a)`
Electric field due to each dipole will be `E=(KP)/(x^(3))`
The direction of electrif field due to each dipole is a shown below:
`E_("net")=E+2E cos 60^(@)=2E`
`=2(1/(4 pi epsilon_(0))) ((2Qa)(x^(3)))=(Qa)/(pi epsilon_(0)x^(3))`