An electric dipole of dipole moment is 6 . 0 × 10 - 6 C m placed in a uniform electric field of 1 . 5 × 10 3 N C - 1 in such a way that dipole moment is along electric field. The work done in rotating

Question

An electric dipole of dipole moment is 6 . 0 × 10 - 6 C m placed in a uniform electric field of 1 . 5 × 10 3 N C - 1 in such a way that dipole moment is along electric field. The work done in rotating dipole by 180 ° in this field will be_______ mJ .

TestHub · Accepted Answer

The work done for rotating a dipole is given by the change in the potential energy. The potential energy is given by
$U = - \vec{p} \cdot \vec{E}$
$W = ∆ U = U_{f} - U_{i}$
So, the work done is
$W = - p E \cos 180 ° - (- p E \cos 0 °) = 2 p E = 2 \times 6 \times 10^{- 6} \times 1.5 \times 10^{3} = 18 mJ$

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