CBSE Class 12-science Answered

Potential energy of dipole placed in electric field is

where p is electric-dipole moment, E is electric field intensity and θ is angle between dipole and direction of electric field .

Work done required to change the dipole from angular position from θ = 0 to θ = 60° is the difference between

potential energy at final position  and potential energy of initial position .

W = U(60°) - U(0) = -p E [ cos60 + cos0 ] = - 2  × 2 × 10³ × [ 0.5 + 1 ] J = - 6000 J

( negative sign indicates work is done on dipole to change angular position  from 0 to 60° ) .