A dipole is placed parallel to the electric field.If W is the work don

1.	A dipole is placed parallel to the electric field.If W is the work done in rotating the dipole by 60 degree; then work done by rotating 180 degrees is
Answer» Given: A dipole is placed PARALLEL to the electric field. W is the work done in rotating the dipole by 60 degree. To find: Work done in rotating 180°. Calculation: GENERAL formula for work done by Dipole in rotation in uniform ELECTROSTATIC Field: $\boxed{ \sf{work = PE \bigg \{ \cos( \theta1) - \cos( \theta2) \bigg \}}}$ While rotating by 60°: $\sf{W = PE \bigg \{ \cos( 0 \degree) - \cos( 60 \degree) \bigg \}}$ $\sf{ = > W = PE \bigg \{ 1 - \dfrac{1}{2} \bigg \}}$ $\sf{ = > W = PE \bigg \{ \dfrac{1}{2} \bigg \}}$ While rotating by 180°: $\sf{W2 = PE \bigg \{ \cos( 0 \degree) - \cos( 180 \degree) \bigg \}}$ $\sf{ = > W2 = PE \bigg \{ 1 - ( - 1)\bigg \}}$ $\sf{ = > W2 = 2PE }$ Dividing the two equations: $\rm{ \therefore \: \dfrac{W2}{W} = 4}$ $\rm{ = > \: W2 = 4W }$ So, final answer is: $\boxed{ \bold{ \large{ \: W2 = 4W }}}$