Magnetic Permeability ... I can't find anyone talking about this !!!!!

[The Observer]

Hello Charlie,

Thanks for your input.

I will consider your response at work today.

Be Well,
            The Observer

[fritz]

Back EMF (electro magnetic force)
is quite easy explained and simple.

Mechanics:
Accelerate a flywheel with a slipping belt and a dc
motor. On turning on the belt will slip, but finally the
flywheel will reach the motor speed. Now the flywheel
is "charged" with rotational energy @ x .rpm.
If you decrease now the dc voltage which powers the
motor - the motor will (wants to) spin slower. Because the flywheel
is turning now faster than the motor - you will get
a pull instead of a push what concerns the belt.
The energy in the flywheel is now consumed by the motor
which wants to turn slower - now the motor turns into a generator
which wants to get rid of the extra energy from the flywheel - by
charging the battery (current reverses).
Well, every motor has a mass and is a flywheel. thats it.

Thats Back EMF, quite simple.

Or accelerate a car - if you release the gas pedal it doesn?t
stand sill instantly, no it slows down - consuming its inerta
versus friction.

Or if you start to run - and want to stop with one step -doesnt
work, you have to destroy the kinetic energy which is stored in
your accelerated body.

[Charlie_V]

If I understood you, you are saying that back-EMF's mechanical equivalent is inertia?  I have to think about this some. 

[fritz]

Ok, lets say you have a traditional dc motor with
high mass spinning at 500 rpm (because u supplied
a voltage x before which causes this speed).
Then you change the voltage (jump) to a value which
would finally ends up in 700rpm.
The motor takes now the same current - as if you
want to accelerate from 0 - 200rpm..
Why ?
The voltage "seen" by the motor - is the input dc voltage
minus the "inner voltage" == back EMF.
The current taken is always (
(outer voltage-inner voltage)/(inner coil resistance).
If outer voltage is lower current reverses.

There are lots of OU setups which somehow tweak around
with inner voltage, resonance and whatever claiming somehow
that in the inner voltage of the motor (in phases with no supply
current) powers back something) - here it gets difficult -

Back EMF itself is very simple.

[Charlie_V]

Your not explaining what back EMF is, just how it works.  I know how it works and yes it is simple.  Very simple, when there is a change in magnetic field through a coil, the coil sets up a voltage.  The polarity of the voltage is such that if current is allowed to flow through a load, the flowing current creates a magnetic field that opposes the initial change. 

This change is geometrically dependent (unlike inertia which is independent - the mass of a weight will fight movement no matter which direction the change comes from).  Back-EMF only fights change that is perpendicular to the cross-sectional area of the coil. 

Back EMF is similar to inertia (or mass we should say since inertia is a mass phenomenon of rotating objects).  Like the mass of a physical object, it does fight change.

I know how the back-EMF(back-Torque - which I equate to the same thing) works but I want to know why.  I feel it is a balancing force, not necessarily a loss.  I THINK its purpose is to balance the energy in the system.  If you can unbalance it, then you might be able to collect or create energy.  It would be the same if you could manipulate the inertia of a rotating object.  Make it such that the force applying the rotation was not effected by the inertia of the object but the inertia of the object was present.  Thus, the mass would gain a momentum but the inertia would not fight the driving force.

The only difference is that I don't see a way of doing this with a physical object, but with a magnet and coil it might be a possibility.