Lenz's law is the EM manifestation of Newton's 3rd law, conserving momentum, and is simply the reciprocal / mutual self-induction of Faraday's law - currents generate magnetic fields, and vice versa; an induced current has its own magnetic field which reacts back with the applied field. It's an EMF - the same force as voltage and the force between two magnets - and its sign is always opposite to that of the applied motion or voltage.
As with Newton's 3rd law, many people miss why conservation of energy should be dependent upon equal and opposite reactions. The reason is that while momentum scales linearly (P=MV), KE scales as half the square of velocity (KE=1/2MV^2) - IOW compound interest on rising speed. From a standing start, we can accelerate 1 kg by 1 m/s using just 1/2 a Joule of energy. But to then increase its speed by another 1 m/s will cost four times the initial price - 2 J. To bump it up again by a third meter per second will cost 4.5 J, and so on. To get it from 9 m/s up to 10 m/s, that same 1 m/s increment of acceleration is gonna cost 9.5 Joules. So why does the cost of KE square up like this? It's because we have to apply the same given force over an ever-increasing displacement, in order to achieve the same consistent acceleration. Alternatively, we could progressively raise the applied force over a constant displacement increment, but either way, the whole joules per meter/sec/kg game is one of massively diminishing returns. The reason is that the force is normally considered as applied from a second, usually non-inertial (non-accelerating) frame - hence there's an ever rising displacement between the thing you're accelerating and the thing it's pushing against. Hence KE rises as half the square of displacement / time. But not so for momentum - since its very units and dimensions are mass times velocity, it scales linearly. Inertia is velocity-independent. So an effective N3 violation would allow you to create energy by effectively towing your reaction mass along for free. Consider two adjacent 1kg masses in free space connected via a perfectly elastic slack tether: an impulse is applied between them, but because abracadabra, only one moves, until they collide again; from either mass's frame of reference, that detail is irrelevant - if we input 1 J of energy then that's all the system has, and whether 1/2 a J resides in each mass or one has more than the other may seem academic... Until we repeat that input condition. A second input Joule will raise the net system energy to just 2J, no OU yet, but from an external FoR the net system momentum has risen by a Joule or so... and as we repeat that input condition, the net system momentum begins to square up, as KE is, by definition, wont to do... while internally, the relative velocity between the oscillating masses never exceeds the linear sum of 1 J/kg/m/s inputs. So when the net system momentum reaches 10 m/s, we'll only have input 20 J of work, but for a 100 J net system energy... IOW we've created 80 J from dodging the usual 1/2V^2 premium. So an N3 violation basically converts the dimensions of our input energy into those of momentum - obviating the 1/2^2 accumulator. We could accelerate a 1 kg mass to 10 m/s using just 5 J (1/2 J per m/s) - a speed at which it'll have 50 J of KE from the stationary reference frame. And exactly this same dynamic applies to EM systems - it's the same fundamental symmetry; a Lenzless motor has a linear input energy for an exponential output KE (RKE = 1/2 angular inertia times angular velocity squared)... therefore beyond some (low) threshold of performance the output energy integral punches diagonally straight through the flat-line input integral, and keeps rising.. Essentially, accelerating a mass Lenzlessly would present no load upon the power supply - only usual resistance losses remain, following Joule's 2nd law for heat (Q=I^2RT where Q = J and I^2RT is current squared times resistance times time)... calorimetry would thus show gains, while a passively superconducting Lenzless reaction could summon infinite free momentum from the vacuum without any incidental heating EM or mechanical, the peak efficiency of an N3 break is a power of ten of whatever's input. In the admittedly spartan world of classical symmetry breaks, an N3 exception would be the motherload. Reactionless propulsion AND free energy. The source or sink is whatever manifests the fields in question (Higgs / virtual photons or whatever vacuum activity they represent).. but either way, an effective N3 violation means a system is thermodynamically open.
