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Consider two thin disks, of negligible thickness, of radius *R* oriented perpendicular to the *x* axis such that the*x* axis runs through the center of each disk.The disk centered at *x = 0* has positive charge density *η*, and the disk centered at *x = α* has negative charge density *-η*, where the charge density is charge per unit area.

What is the magnitude *E* of the electric field at the point on the *x* axis with *x* coordinate α*⁄2* ? Express your answer in terms of *η, R, α*, and the permittivity of free space *∈ _{0}*.

*η*and the area could be subdivided into charge elements of the surface

*dq=ηds*where

*ds*is the underlying element of the surface.

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