For an electric dipole, the product qd is called the dipole moment and is given the symbol p. Here d is the distance between poles and q is the magnitude of the charge on either end. The dipole moment vector has a magnitude of qd and, by convention, points from the negative to the positive end. Assuming an electric dipole is free to move and rotate and starts from rest,
(a) use a sketch to show that if it is placed in a uniform external field , it will begin to rotate so that tries to “ line up” with .
(b) Show that the magnitude of the torque exerted on the dipole about its center is given by τ = pE sin θ, where θ is the angle between and p-bar and E-bar.
(c) What is the net force on this dipole?
(d) For what angle(s) is the torque at its maximum? What about at its minimum?