Does a rotating magnetic field possess angular momentum in the direction of rotation? I suppose this comes down to a broad question about the physical nature of fields in general. I love the Einstein-de Haas effect, where an iron core spins in the opposite direction of the induced spin angular momentum of the electrons producing the field. That’s all very clear and intuitive. And that got me wondering about the case of a rotating magnetic field. Let’s say we have an iron toroidal core with a series of coils around it (let’s say that there’s an air gap between the coils and the toroid, and the toroid is somehow floating freely inside them), as depicted in Fig. 16-13 of this Feynman Lecture: http://www.feynmanlectures.caltech.edu/II_16.html Now we induce a rotating magnetic field. Will the iron core rotate in the opposite direction? Maybe I’m mistakenly thinking of a magnetic field as a form of “stuff,” which has its own independent physical properties like angular momentum when rotated. It’s perplexing because this page discusses the momentum of fields stored in space, but the directions of the flow are still counter-intuitive to me: http://www.feynmanlectures.caltech.edu/II_27.html If anyone can shed some light on this I’d really appreciate it; I can’t find any good references to help me figure out how to think about this question.