A dipole , with a dipole moment of magnitude p, is in stable equilibrium in an electrostatic field of magnitude E. Find the work done in rotating this sipole to its position of unstable equilibrium .

Explanation

A dipole in an electron field at stable equilibrium position corresponds to `theta = 0^(@)` .
A dipole in an electric field at unstable equilibrium positin corresponds to `theta = 1980^(@)`
` :. `The work done ` = int_(theta =0^(@))^(theta=180^(@)) pE sin theta d theta `
`= pE [ -costheta]_(0^(@))^(180^(@))=2pE` .