An electric dipole consists of charges 5e and 5e separated

An electric dipole consists of charges +5e and - 5e separated by 2 mm. If the electric field of strength 5.2 X 10^6 N/C is applied to the system, calculate the magnitude of the torque on the dipole when the dipole moment is perpendicular to the electric field.

Solution

force on each charge will be F = qE

torque = (r x F)

net torque = 2(rF) = 2rqE = dqE

= 2 x 10^-3 x 5 x 1.6 x 10^-19 x 5.2 x 10^6

= 8.32 x 10^-15 N m