What is the Magnitude of the Dipole Moment in a Uniform Electric Field?

[nothingatall]

Homework Statement

A certain electric dipole is placed in a uniform electric field E of magnitude 20 N/C. Figure 22-59 gives the potential energy U of the dipole versus the angle θ between E and the dipole moment P. What is the magnitude of P?

Homework Equations

U=p(dot)E

The Attempt at a Solution

Somehow there is an integral needed to solve this but I don't know where to start. there is also a graph with this question.

 

[minimark1234]

i thought...
U=-\vec{p} \cdot \vec{E}
but idk if that really changes much.

 

[nothingatall]

It does, i was just forgetting to multiply it by the factor of 10^-26 hehe. Thanks.

 

[slamin27]

can't you just take Us to be the maximum, and the angle of 180 to be the angle that corresponds to the maximum potential, and plug these into U=-pEcos(theta), along with the magnitude of E?