Physics

Problem

A dipole with moment

2.0\times10^{-30}\,\text{C\,m}

is initially perpendicular to a uniform electric field of magnitude

1.0\times10^{5}\,\text{N\,C}^{-1}

. It is first rotated to become antiparallel (

180^{\circ}

) and then further rotated to become parallel (

0^{\circ}

) to the field. What is the total work done by an external agent in carrying out the complete rotation from

90^{\circ}

0^{\circ}

via

180^{\circ}

? a)

+4.0\times10^{-25}\,\text{J}

-4.0\times10^{-25}\,\text{J}

-2.0\times10^{-25}\,\text{J}

+2.0\times10^{-25}\,\text{J}