Physics Question on Electrostatic potential

Question

The increase in electrostatic potential energy of a dipole of moment p when it is taken from parallel to anti-parallel orientation in an electric field E is

Answer 1

Solution

p = dipole moment
U = - pEcos $\theta$
$U_{1} =-pEcos0^{\circ}$
$U_{2} =-pEcos180^{\circ}$
$\Delta U =\left(U_{2}-U_{1}\right)=pE +pE=2 pE$
Increase in potential energy $\Delta U =2 pE$