Lenz's law

 in electromagnetism, statement that an induced electric current flows in a
direction such that the
 current opposes the change that induced it. This law was deduced in 1834 by
the Russian physicist
 Heinrich Friedrich Emil Lenz (1804-65).

 Thrusting a pole of a permanent bar magnet through a coil of wire, for
 example, induces an electric current in the coil; the current in turn sets
 up a magnetic field around the coil, making it a magnet.  Lenz's law
 indicates the direction of the induced current. Because like magnetic poles
 repel each other, Lenz's law states that when the north pole of the bar
 magnet is approaching the coil, the induced current flows in such a way as to make the side of the coil nearest the pole of the bar
 magnet itself a north pole to oppose the approaching bar magnet. Upon
withdrawing the bar magnet
 from the coil, the induced current reverses itself, and the near side of
the coil becomes a south pole
 to produce an attracting force on the receding bar magnet. A small amount
of work, therefore, is done in pushing the magnet into the coil and in
pulling it out against the magnetic effect of the induced current. The small
amount of energy represented by this work manifests itself as a slight
heating effect, the result of the induced current encountering
 resistance in the material of the coil. Lenz's law upholds the general
 principle of the conservation of energy. If the current were induced in the
 opposite direction, its action
would spontaneously draw
 the bar magnet into the coil in addition to the heating effect, which would
 violate conservation of energy.


Basically its making the core a stronger magnet and thus a stronger
magnetic force is working against the turning force.

<p> You can also see this force by dropping a neo magnet down through
a copper tube and see that it falls slowly due to this Lenz counter
to motion force. Also by moving a neo magnet on the flat surface of
aluminum bar you will feel this resistance no matter what direction
you move the magnet.
<p>


My 1960's vintage Amsco School Publication -
"Reviewing Physics" says

Lenz's law -
p. 249 when the N-pole of the permanent magnet is thrust throught
the coil of wire the current flows about the coil in a counterclockwise
direction. Therefore, the end of the coil adjacent to the N-pole of the 
magnet becomes N-pole. 
 - and the figure 149 on p 248 shows a N magnet going into a counter
clockwise wound coil with an induced current flow that makes a N
pole magnet at the near end of the coil
  and thus repelling it and resisting the direction of motion.
  When the magnet is withdrawn, the poles
of the coil reverse giving a S pole which attracts and resists the
direction of motion - ie Lenz law.
<p>
then p. 249
Lenz's law -
"An induced current flows in such a direction that it will oppose by its 
magnetic field the motion of the magnetic field which is producing it."

(Neb so that would be a coil generated magnetic field that pushes against the
originating magnetic field)

But what I would like to know now is how strong is it?
.....
<p>
Below are an accumulation of notes and thoughts.....



Basic Electricity Book p. 5-4 Lenz's law

The induced voltage or emf will be such that the resulting current flow will
build up a field to react with the field of the magnet and oppose the
movement of the coil.
What happens to the field that was there? Is it overpowered?
Is it mixed with it giving a net differenct?


World Book Lenz's Law p. 175 says in an electric generator, the (flowing Neb
) current produced creates a magnetic field that opposes the action of the
force that produces the current. so (added work Neb) must be done to keep
the current flowing or the (counter force will stop the device from
turning).


the physics web site says that
 small magnets align them selves such that they are aligned against
  the permanent magnet polarities and push against (like poles)
  the permanent magnet
  so the current creates little magnets
is it the magnetic field that creates the current?
  it can't be because that is probably cancelled/countered when
  the Lenz's law counter forces (like poles) are created

its the current flowing that makes the counter magnetic pole force
the pendulum tests show this.

does a cored coil and a coreless coil produce the same voltage
 polaritites?



what would a bifilar coil do to this???
   do a pendulum test to see...
   would it have current too???
   or would the current stop too....