Two point charges +Q and -Q of mass m are placed on the ends of a massless rod of length L, which is fixed to a table by a pin through its center. If the apparatus is then subjected to a uniform electric field E parallel to the table and perpendicular to the rod, find the net torque on the system of rod plus charges.

1 answer

Torque depends on the orientation of the dipole in relation to the E field.
In a vector sense, torque=qL X E (Where X means cross product)