Find the interaction force between two water molecules separated by a distance `l = 10 mm` if their electric moments are oriented along the same straight line. The moment of each molecule equals `p = 0.62.10^(-29) C.m`.

Explanation

Force on a dipole of moment `p` is given by
`F = | varphi (del vec(E))/(del l)|`
In our problem, field, due to a dipole at a distance `l`, where a dipole is placed,
`|vec(E)| = (p)/(2pi epsilon_(0) l^(3))`
Hence, the froce of interaction,
`F = (3 p^(2))/(2pi epsilon_(0) l^(4)) = 2.1xx10^(-14) N`