Given,
q1=3.2×10−19 C , q2=−3.2×10−19 C
Seperation between two charges d=2.4×10−10 m
From the data given in the question,
Dipole is placed in a uniform electric field of intensity E=4×105 V/m
Workdone in rotating the dipole by angle θ is given by
W=pE(1−cosθ)
But , given θ=180∘.
∴W=pE[1−(−1)]=2pE
⇒W=2(qd)E
Substituting the given values we get,
W=2×3.2×10−19×2.4×10−10×4×105 J
⇒W=61.44×10−24 J
Comparing this with , x×10−24 J we get, x=61.44
Accepted answers: 61 , 61.4 , 61.44