Hello. I want to ask you about an idea to get a free coil movement when it's moving on a specific magnetic field, and at the same time it also gives electric energy... and without replacing the energy from outside... OK, Don't be scared with these statements, and please read the idea. Then, if you consider it is wrong, please tell me why. We will start with elemental physic: Magnetic induction says that the field generated on a coil that is inmersed into a variable magnetic field always opposes the change on that magnetic field. From this point of view, magnetic induction is an inertia or tendency to oppose magnetic changes. Usually, the aproach of a magnet pole (either north or south pole) to a coil increases the field on the coil, and their sepparation decreases the field on the coil, so magnetic induction is always seen as an opposing force to movement. But... ¿What about a way to increse the field when the magnet is leaving the coil, and decrease it when the magnet pole is approaching? In this case, the usual mechanical opposition would turn into a mechanical force of acceleration for the coil! I've attached a schema of such a system: We have a track with alternated polarity magnets. Then, imagine you move a coil perpendicular to the magnets, from the left to the right of the picture. 1 - We start at the middle of the north pole of a magnet. As the coil LEAVES the north pole magnet, the field INCREASES (instead of decreasing as usual). The coil tries to avoid the field increase, and then it creates a north pole... Directed to the north pole of the magnet that it is leaving!, so we have REPULSION, and then the coil MOVES AWAY the north pole magnet. 2 - When the coil arrives at the area between two magnets, the field is maximum, but there is no magnetic induction (so no force). 3 - Then, the coil APPROACHES to a south pole magnet. Usually, the field should increase, then the magnetic induction would create repulsion, restraining the coil... but in our case, the field DECREASES as the coil approaches, so the coil opposes this change generating a north pole directed to the south pole magnet, that is to say we have magnetic ATTRACTION, so the coil APPROACHES more to the south pole magnet. 4 - Now, when the coil gets to the middle of the south pole magnet, magnetic change and induction are at their maximum values... but there is no field crossing the coil. 5 - When the coil LEAVES south pole magnet, usually we should see a decreasing field, but in our case, the field INCREASES!, So the coil opposes to it, and generates a south pole directed to the south pole magnet. Then we have REPULSION between magnet and coil, so the coil MOVES AWAY from the south pole magnet. 6 - Finally, the coil APPROACHES a north pole magnet, the field crossing the coil should increse, but it DECREASES. The coil opposes this magnetic variation generating a south pole directed to the north pole magnet, so there is ATTRACTION between them. The coil APPROACHES to the north pole magnet, till it gets to the middle of the north pole magnet, where the magnetic change, and thus the induction are maximum, but there is no field crossing the coil. Then the sequence repeates. I mean, as we have inverted the usual relation between coil movement and magnetic field variation in the whole track, we have the magnetic induction creating a mechanical force of acceleration instead of restraining the coil!... and we have also the electric energy of the induction itself!. The coil gets accelerated when moving into the track, and also it extracts electric energy from the induction! (??) You could think that at the same time you have the coil generating a magnetic pole to accelerate it, you have the other side of the coil generating the opposite pole, and then you've got acceleration into the other direction, restraining the coil... but the distance between the coil and the previous magnet is always greater than to the next magnet, so the accelerating force is always greater than the restraining force. What do you think?