- #1

schattenjaeger

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**p**1 and

**p**2 located at

**r**1 and

**r**2 respectively(all four are vectors)

what's the energy of

**p**2 in the field of

**p**1?

I know the general expression for the energy of a dipole in an external field

**E**o is U=-

**p * E**o but from there I get confused

I can express the electric field of the dipole in terms of its radial and angular components, but I'm not sure how to express

**p**2 in those same terms.

FYI the answer is Udd=1/(4pi*epsilon*R^3)*[

**p1*p2 - 3(p1*R)(p2*R)**]

both those bold Rs are unit vectors, * is dot product if it's between two vectors