An electric dipole moment `p` is placed in an electric field of intensity `'E'`. The dipole acquires a position such that the axis of the dipole makes an angle `theta` with the direction of the field. Assuming that the potential energy of the dipole to be zero when `theta= 90^(@)`, the torque and the potential energy of the dipole will respectively be

Options

A. `pE sin theta , -pE cos theta`
B. `pE sin theta , -2pE cos theta`
C. `pE sin theta , 2pE cos theta`
D. `pE cos theta , -pE cos theta`

Answer

A

Explanation

`vectau = vecp xxvecE implies |vectau| =pE sin theta`
`U = -vecp . vecE implies U =-pE cos theta`