My statement was clear--inductance causes BEMF, and BEMF is an effective circuit resistance.

It would be more accurate to say that BEMF causes an "effective resistance"

**to changes** of electric current.

However, this "effective resistance" IS the "inductive reactance".

Q:So what is the difference between resistance and reactance?

A: The distinction is very simple: resistance opposes the

**instantaneous** current (i) and reactance opposes the

**change** of current (di/dt).

...impedance only comes with inductance,

Not only - impedance also comes with capacitance.

Formally, impedance = resistance + reactance. (Z=R+X). The first component is commonly called the real component, the second component is called the imaginary component, and their sum is called the complex quantity (...or complex impedance).

Also, the quality factor of a coil is equal to Q=X/R.

...and inductance creates that impedance-->BEMF

Actually, pure inductance creates only the imaginary component of the impedance. Pure inductance does not create the real component of impedance.

...and BEMF is an effective resistance(impedance) to current flow.

Not precisely - BEMF causes an opposition

**to changes** of electric current flow. That is very different than "an opposition to the current flow".

*The statement that if a coil has no resistance, it has no inductance is incorrect. All coils have inductance.*

Once again,very wrong.

I have just finished testing a coil that has no inductance,against an identical coil,but which has inductance

The current trace through this coil is vertical,unlike the coil with inductance which is on a linear incline.

But that only proves, that it takes electric energy to create magnetic energy.

It doesn't prove that zero resistance causes zero inductance, which is the implication that Poynt objects to.

One coil produces a BEMF,and the other dose not.

That only proves that one coil has inductance and reactance, while the other does not.

One coil produces a magnetic field,the other dose not.

That only proves that one coil has inductance while the other does not. Inductance is best conceptualized as the ratio of magnetic flux to electric current, L=Φ/i

One coil dissipates more power than the other--can you guess which one dissipates more power?.

Of course, the one that has less inductance, because inductance is responsible for conversion of electric current into the magnetic flux...and the more electric current gets converted to magnetic flux, the less electric current is converted to heat by the resistance.

And if the current dose not change over time,but go's straight to it's maximum value at T=0,then there is no reactance,no inductance,no magnetic field,and no BEMF.

Yes

It is the inductance that creates BEMF-the coil self induces. The impedance is a result of the self induced BEMF.

This is correct but not precise enough. Since impedance consists of two components: resistance and reactance (Z=R+X) and pure inductance is capable of presenting reactance only, then it would be better to write that:

"The reactance is a result of the self-induced BEMF"

If the superconductive inductor has inductance,then it will also have BEMF.

Yes, but the BEMF in a superconducting coil is also a victim to the infinite time constant Tau=L/R and as a consequence it

**perpetually** opposes any change of current. Because of this infinity, the normal proportionality of BEMF to the rate of change of current (di/dt) degenerates to the proportionality to the absolute value of current (i).

Such is the fate of the very concept of "change" when the RL circuit's time stops due to Tau=∞.

No time flow = No change = No BEMF decay.

If it has BEMF,then its **effective resistance** value is not 0, as the BEMF will resist the **change to** the flow of current.

Yes, but the proper name for the "effective resistance" IS "inductive reactance".

Also, when Tau<∞, BEMF does not oppose the absolute value of the current, it opposes

**the change** of this current. I allowed myself to make this addition to your sentence in green color in your quote above.

So,when a superconducting coil,that has 0 resistance is dropped across a battery,and because of the 0 resistance no voltage exists across the inductor, we then calculate ~~power~~ **energy** by multiplying the current by 0 volt's?

We can calculate the energy stored in the coil by measuring its magnetic field with a magnetometer (Hall, GMR, AMR, TMR, etc...)* and calculating the energy as E=½Φ

^{2}/L, without disturbing the coil's circuit.

Alternately, we can calculate the energy stored in the coil only by considering only its inductance and current E=½Li

^{2}, but since a superconductive coil has an infinitely long time constant Tau, the current from the battery will take infinite time to rise if such coil is charged by such electric means.

You could, however, charge the coil with energy by opening its curcuit, putting a magnet in it, shorting it, and pulling the magnet out ...or shorting it, heating it up until it loses superconductivity, putting a magnet in it, freezing it until it gains superconductivity and pulling the magnet out.

In both scenarios, the superconducting coil will be left with a perpetually circulating electric current that will maintain the same flux, that the magnet was providing before it was pulled out. This is an example of a "pull out technique", that does work.

To impede-->HINDER, IMPEDE, OBSTRUCT, BLOCK mean to interfere with the activity or progress of. HINDER stresses causing harmful or annoying delay or interference with progress. IMPEDE implies making forward progress difficult by clogging, hampering, or fettering

To resist--> counteract or repel ,mean to set against something,to hinder progress,to fight against,to limit,

As you can see both of these words have similar meaning in non-technical jargon.

However, in electrical engineering impedance is the sum of resistance and reactance (Z=R+X).

And the most significant difference between resistance and reactance is that the former is proportional to current (i) and the latter is proportional to the rate of change of current (di/dt).

*

^{Since magnetometers measure the Magnetic Flux Density (B) and not the total Flux (Φ), their measurements need to be integrated over an area (in sq.meters) in order to yield Flux.}