# Potential energy of the dipole-dipole interaction for two parallel dipole moments

I am looking for an equation that gives me the potential energy of the interaction between two parallel dipoles.

• This is pretty much formula based. Find the field due to one dipole near the other, then use $U=-\vec p \cdot \vec E$ – udiboy1209 Jul 24 '13 at 11:15
• I think, according to homework policy, this question is off-topic. – Mostafa Jul 24 '13 at 11:18

$$U=\frac{1}{4\pi \epsilon_0r^3}\left( \mathbf{p}_1.\mathbf{p}_2-3\left ( \mathbf{p}_1.\hat r )(\mathbf{p}_2.\hat r\right) \right)$$
• Could you explain what is the meaning of $\hat r$? – user1420303 Nov 14 '18 at 14:28