An electric dipole of moment p is lying along a uniform electric field E . The work done in rotating the dipole by rotating the dipole by 90 degrees:

Correct answer: (A) p E. Work done W =∫_0^θ P E sin θ d θ =P E(1-cos θ) ∴ Since θ =90^° W =P E(1-cos 90) Q =P E

Q119 / 200 · NEET 2006 · Physics

An electric dipole of moment $\vec{p}$ is lying along a uniform electric field $\vec{E}$. The work done in rotating the dipole by rotating the dipole by 90 degrees:

Correct answer
A
$p E$
B
$\sqrt{2} p E$
C
$p E / 2$
D
$2 P E$

Solution

Work done $$ \begin{aligned} W & =\int_0^\theta P E \sin \theta d \theta \\ & =P E(1-\cos \theta) \\ \therefore \quad \text { Since } \theta & =90^{\circ} \\ W & =P E(1-\cos 90) \\ Q & =P E \end{aligned} $$

Hence, the correct answer is option: 'A'.

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