An infinite line charge of uniform charge density λ  is held fixed along the Z-axis of a Cartesian coordinate system. A point electric dipole initially kept at the point A(+a, 0, 0) with the dipole moment P→  along the negative X-direction is moved to the point B(2a,0,0) and rotated so that its dipole moment along positive x direction. The work done by the external agent on the dipole in the entire process is