Hello. I have problems with the Faraday and Lenz laws. Not problems with their definitions (they are OK), but with the usual assumptions and relation with conservation of energy: The definition of these two laws states: - Faraday law: The induced electromotive force or EMF in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. - Lenz law: The induced emf and the change in flux have opposite signs. OK. Also, we know 3 ways of changing flux on a closed loop: moving a magnetic field over the closed loop, changing the field intensity, or changing the closed loop surface. My problems come with the first method of magnetic induction: moving a magnet over a coil. Usually, we say that the EMF opposition on the coil opposes the movement of the magnet, because (usually) flux increases when poles come closer to the coil, and decrease when they leave. But the Faraday/Lenz law has nothing to do with "movement". They state that the EMF opposes flux variation, nothing more, nothing less. (... And, of course, nothing about movement here) Usually we say that opposition to flux change is the same as opposition to movement, because the magnetic flux is always "linked" to magnet poles... That is right. But there is a method to have the flux SEEN BY COILS "out of phase" respect magnet movement (flux is really linked to magnet poles, but not linked to how it traverses the coil surfaces). If we get the flux "out of phase" respect to movement, the Lenz force will oppose to the flux variation, as usual... but no longer to the movement! In this case, the Lenz force could in fact accelerate the magnet movement instead opposing it! The way to get flux increasing when the magnet poles are leaving, and get the flux decreasing when a magnet pole is approaching is... just placing the coil surfaces perpendicular to magnet pole surface while the magnet rotates. For example, there is an illustrative experiment to show the classic Lenz force opposition to movement, that consist in throwing a magnet through an aluminium or copper tube. As the magnet go down the tube due to gravity, the flux changes in front and behind the magnet in such a way that the Lenz force opposes the flux change... and also the movement. The final effect is that the magnet slows down when going through the tube. BUT... What about a magnet rotating inside the hole of an aluminium or copper toroid? (just like the hands in a clock) You can see that this way, the flux change on the toroid sections is "out of phase" respect the magnet rotation. The increase of the flux is not "attached" to a magnet pole approaching (in fact, the increase of the flux happens when the poles leave that section!) and the decrease on the flux happens when magnet poles approach to a given section of the toroid!! In such a case, the Lenz force will do what is stated to do: oppose the flux change... but as the flux is "out of phase" from the magnet pole movement... the Lenz force will accelerate the magnet!!! I know that Lenz law is always seen related to conservation of energy in electric systems, but you can see that there is something wrong in the usual assumption of "opposition to flux change" being equal to "opposition to movement". If we manage to get these two concepts "out of phase" we can't say that opposing one is opposing the other. ... What do you think?