MAGNETIC FIELDS IN MATTER — Edward Purcell & David Morin
Physics — E&M · dipole-potential-energy
Problem
Find the potential energy of the first and third dipole configurations in Exercise 10.29 (the second and fourth require only a slight modification), by explicitly looking at the potential energy of the relevant pairs of point charges in the dipoles, and then making suitable approximations. Let the charges q and −q in each dipole be separated by a distance ℓ, and let the centers of the dipoles be separated by a distance d (with ℓ≪d).