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## Homework Statement

assume that two dipoles are placed back -t0 - back along axis as shown:

((-) a (+))(( +) a (-)) ------------------x axis

r is oriented between ))(( but above, a distance such that r>>a

compute the strength of the electric field on the axis of the pair at a distance r away from the the center of the dipole pair. use the approximation r>>a to simply your expression. each charge can be assumed to be 1 microcoulomb charge with the sign shown in the diagram

## Homework Equations

electric potential V = kq/r where k is 9*10^9 constant, q is charge in coulombs, r is distance the charge is from the point r

electric field E = 2kP/r^3 where P is the dipole moment, given as 10^-8 C-m -->derivative of electric potential eq

## The Attempt at a Solution

i am not sure where to draw the diagram as shown with lines connecting each charge (4 of them) and using the V equation to sum them up, but r is not given a numeric value

then do i do the derivative of the summation of V?

or do i just use the electric field equation, but how do i involve all four charges, and what do i put in for r in the denominator?

any help appreciated

cheers...