How to Calculate Potential Energy Difference for a Dipole in an Electric Field?

[loba333]

Homework Statement

A molecule of water has a dipole moment of 6.1×10^–30 C m. Calculate the difference in potential energy between when its dipole is parallel to an electric field of 2.0×10⁵ V m^–1 and when it is anti-parallel to the field.

Homework Equations

U=kq1q2/r
V=U/q
V=Ex

The Attempt at a Solution

If the charge on each side of the dipole is just 1.6x10^-19 ill be able to do the problem i think. other than that i have no idea what to do.
i was guna divide the dipole moment by 1.6x10^-19 to give me the diameter of the molecule. then just use U=kq1q2/r

Help me please and add any helpful infomation

Thankyou

 

[gneill]

Investigate dipole moments in electric fields, and in particular the torque that obtains for a given angle of the dipole moment vector to the electric field vector.