Explain the position (orientations) of a dipole in stable equilibrium, unstable equilibrium.

Explanation

The potential energy of a dipole place in uniform electric field,
`U = -vecP.vecE=-pEcos theta`
where `theta ` is an angle between `vecp` and `vecE` .
(i) If ` vecp||vecEimplies theta=0^(@)`
`:.` U = -pE is the stable equilibrium state of a pole .
(ii) If `vecp ||(-vecE)implies theta=180^(@)`
`:.` U = pE is the maximum value of potential energy which indicates unstable equilibrium state ofa dipole.
(iii) If `vecP bot vecEimplies theta= 90^(@)`
`:.` U=0
which indicates maximum unstabl equilibrium state of a dipole.