look at the figure in the attachment(adsbygoogle = window.adsbygoogle || []).push({});

The black dots at the ends of the square in the figure represent charges -q or +q and they are denoted + or - by the symbol next to the them.

Now that line is drawn from the centre of the square to point P and is distance x

The side of the square is 2a

Show that Electric Field at P for x >> a is 3 (2qa^2) / 2 pi epsilon0 x^4

so far i came up with this

for the dipole closer to P the expression would be

E = (1/4 pi epsilon) 2qa/ [(x-a)^2 +(2a/2)^2]^3/2

and after a lot of algebra i get

E = (qa / 2 pi epsilon ) * 1 / [ x^2 + 2xa + 2a^2]^3/2

for the first closer dipole

for the more distant dipole i get E = - (1/4 pi epsilon) 2qa / [ (x+a)^2 + a^2 ] ^3/2

more algebra i get E = - (qa / 2 pi epsilon ) * 1 / [x^2 + 2xa + 2a^2]^3/2

but it is after this point that i am stuck completely

how do i get to the expression that is needed??

please please help!

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Problem on electric field due to dipoles

**Physics Forums | Science Articles, Homework Help, Discussion**