Lenz's law can be violated.

[pese]

tks all for your help. given the links.
That was nearby all that i looked for.

My thanks and given:

usuakyy are lambda diodes made with 2 fets.
i find one circuit that use 1 fet and one transistor !!!
Because its so unusual and rare . i will deal this to
all interesting guys.


it was stored in my circuit collectin in the web
(so i have found it again...)

http://alt-nrg.de/pese/PX/LambdaRahmenSchalt.jpg Lambda-Diode/neg Widerstand Fet+Trans


http://alt-nrg.de/pese/PX/neg2.jpg dito m 2 Fets

[neptune]

@EMdevices . Could you please explain the function of the cored choke in your diagram in reply number 1 of this thread . Also my knowledge of the magnetic properties of ferrite is zero . Are you saying , in simple terms that the ferrite rod needs to be saturated? nearly saturated . Would there be an advantage in being able to vary the DC bias current to find the "sweet spot" ? Assuming that DC bias is used rather than a permanent magnet , would a ferrite toroid be better than  a rod , as in the youtube vid , a link to which appears on page 1 of this topic . If there is any possibility this vid is real , the guy is lighting 2 LEDS without a battery , just a permanent magnet .I would like some help to replicate this , please .

[kmarinas86]

It is possible for a permanent magnet to induce a current into a wire loop having the same polarity, but the angles in which this is possible is strictly limited.

Here is a diagram with a wire loop at the top and a magnet at the bottom.

"OUT OF THE PAGE"
....|
....|
....|
"INTO THE PAGE"


.......N
....../
...../
..../
..S

Let's say the permanent magnet is rotating counter-clockwise with pivot of rotation at the center of the magnet.

We know that the force of a magnet decreases with the cube of the distance from each pole, which is due to the dipolarity of the magnet.

We also know that the field lines will rotate with the rotation of the magnet. The speed of these field lines increases linearly with the distance of the magnet.

Thus, B decreases with the cube of the distance, and v increases linearly with the distance.

Because the magnetic component of the Lorentz force is proportional to the cross product of v and B, which is |v||B|sin(theta), then the induced force on charge on the part of the loop where it says ("INTO OF THE PAGE") in the diagram will be greater than that on the part of the loop where it says ("OUT OF THE PAGE") [Note: "INTO OF THE PAGE" is closer to the permanent magnet than "OUT OF THE PAGE"). Interestingly enough, combining an inverse cube law with a linearly increasing law gives you an inverse square law.

By observing the Lorentz force law for (-) charge (http://commons.wikimedia.org/wiki/File:Lorentz_force.svg), we can find that what I labeled ("INTO THE PAGE") is in fact the direction that the (-) or electron current will go (i.e. "INTO THE PAGE"), and we find that what I labeled ("OUT OF THE PAGE") is in fact the direction that the (-) or electron current will go (i.e. "OUT OF THE PAGE"). Using the right hand rule, or preferably the TWO-HAND rule, we can find out the polarity produced by the induced current:

"(-) OUT OF THE PAGE"
.....|
...N|S
.....|
"(-) INTO THE PAGE"


......N
......|
......|
......|
......S

As you can see, the N of the permanent magnet and the S of the (-) or electron current in the loop are orient in such a way that they would turn into each other. Extending this in time however, and in this case, after the loop rotates a full 90 degrees:


OUT--IN
......|
......|
......V
......N

......N
......|
......|
......|
......S

Opposite polarity now appears because as N approaches the loop, the lines of the permanent magnet "focus" and concentrate to where the loop is, and so the lines of the magnet cut through from the outer periphery of the loop. This causes the current to reverse direction from where it was. Now the loop repels the permanent magnet instead of attracting.

The point is that the kinetic energy or work done a permanent magnet may produce magnetic fields which may be either aligned to it or aligned against it.

IMHO, oscillation between such attractive and repulsive modes can be a physical, mechanical explanation for diamagnetism as well as the levitation (and "stickiness") of superconductors. It's amazing what classical physics can explain.

[neptune]

@kmarinas86 . Thanks for that lengthy explanation . However , I am not sure just how relevant it is to the current topic , as here , we have no relative movement between the coil and the magnet , or electromagnet . The only thing that is "changing " is the alternating current in the tank circuit .