Field line motion in classical electromagnetism

We consider the concept of field line motion in classical electromagnetism for crossed electromagnetic fields and suggest definitions for this motion that are physically meaningful but not unique. Our choice has the attractive feature that the local motion of the field lines is in the direction of the Poynting vector. The animation of the field line motion using our approach reinforces Faraday’s insights into the connection between the shape of the electromagnetic field lines and their dynamical effects. We give examples of these animations, which are available on the Web.