Question

An electric dipole of length 2 cm is placed with its
axis making an angle of 30° to a uniform electric
field 10^5 N/C. If it experiences a torque of
10√3 Nm, then potential energy of the dipole
(1) – 10 J
(2) - 20 J
(3) – 30 J
(4) - 40 J​

Answer 1

U=-pEcosx

τ=pEsinx

10√3=pE*1/2               (sin30=1/2)

pE=20√3

substituting its value is the first equation

U=-pEcos30

=-20√3*√3/2

=-10*3

=-30 J

therefore your answer is option 3

Hope this helps