An electric dipole made up of a positive and negative charge, each of $1\mu \mathrm{C}$ separated by a distance of 2cm is placed in an electric filed of${10}^5$  N/C, then the work done in rotating the dipole from the position of stable equilibrium through an angle of ${180}^0$  is

Given data: Dipole with a positive and negative charge separated by a distance 2cm

Concept used: Electric dipole 

Detailed solution:

We know that Potential energy u = -P.E

Now the work done W = ΔU

$=\left(-P.E \cos {\theta }_2\right)-\left(-P.E\cos {\theta }_1\right)$

$=\left(-P.E\cos 180\right)-\left(-P.E\cos \theta \right)$

=2P.E

$=2\times \left(1\times {10}^{-6}\times 2\times {10}^{-2}\right)\times {10}^5$

$\Rightarrow W=4\times {10}^{-3}J$