Question

A short electric dipole of dipole moment P is
placed in stable equilibrium in uniform electric
field E as shown in the figure. The work done
by the external agent to rotate the dipole slowly
up to its unstable equilibrium will be?

(1) PE
(2) 2PE
(3) underoot3 PE/2
(4) zero
​

Answer 1

Zero is the correct answer

Answer 2

Answer:

W = 2pE

Explanation:

Work done in rotating the dipole from the position of stable equilibrium to unstable equilibrium, i. e. When theta 1 = 0° and theta 2 = 180°

W = pE ( cos theta 1 - cos theta 2 )

W = pE ( cos 0° - cos 180° )

W = pE ( 1 - ( - 1 ))

W = pE (2)

W = 2pE