A particle of charge q1 is at rest at the origin. A second particle, of charge q2, moves along the z axis at constant velocity v.
(a) Find the force F12(t) of q1 on q2, at time t (when q2 is at z=vt).
(b) Find the force F21(t) of q2 on q1, at time t. Does Newton's third law hold, in this case?
(c) Calculate the linear momentum p(t) in the electromagnetic fields, at time t. (Don't bother with any terms that are constant in time, since you won't need them in part (d)). [Answer:(μ0q1q2/4πt)z^]
(d) Show that the sum of the forces is equal to minus the rate of change of the momentum in the fields, and interpret this result physically.