basic defnitions

Anyone who produces precise definitions will produce definitions identical to those in any text book. Only sloppy, non-mathematical will differ.

I'll take a crack at the first one and see if that does you any good.

Inductance is what we call the relationship between a current through some path and the amount of energy stored in the magnetic field produced by that current and wrapped around it. Altering the path of the current (i.e. coiled wire versus straight wire) or the environment around the current (i.e. core material permeability) alters the inductance of that path.

E=(L*I^2)/2, where E is energy in joules, L is inductance in henries and I is current in amperes.

The process of putting that energy into the magnetic field or extracting energy out of it produces a unique relationship between the current through the inductance and the voltage across it. This process takes time, and can be expressed either in terms of rate of change of current or integral of voltage over time.

V=L*(di/dt), where V is the instantaneous potential across the inductance in volts, L is the inductance in henries, and di/dt is the instantaneous rate of change of current through the inductance in amperes per second.

If you integrate both sides of that equation, you get the integral form:

I(t)=(1/L)*integral of V(t), from t0 to t1, + I0

I0 is the initial current at time t0, I(t) is a description of current from time t0 to time t1, V(t) is a description of voltage from time t0 to time t1. If you don't know what an integral is, then this whole thing is gibberish.

Writing a proper integral expression in text is not so easy, so you should see this formula in a proper reference like:

But the general idea is that to get from one current (I0) to some other current (I1) over some period of time (t1-t0), you must have some average voltage applied across the inductor during that time, and the higher the inductance, the higher the average voltage required to swing the current through that amount of change.

I hate to plow on unless I am getting through with this much.

What don't you like about the textbook answers? Too detailed? Too light on detail? You're too cheap to buy books?

Misspelling of inductance. It's the electrical effect arising from the magnetization and demagnetization of a bit of space or a bit of iron or ferrite material. Apply voltage, current rises, remove voltage, current stays the same (decreases in a real inductor because of resistance), open the circuit, voltage goes up and up until current _does_ flow dammit! (Inductors say "dammit" by making a spark).

The mirror of inductance. It's the electrical effect arising from an electrical field getting stored in a bit of space or dielectric. Apply current, voltage rises. Remove current, voltage stays the same (for much longer than with a reasonable-sized inductor, by the way). Short circuit the capacitor, much current flows very briefly -- this is usually less dramatic than the spark from an inductor, but the level of drama depends heavily on the circuit.

When you apply an AC voltage (or current) to a circuit you generally get an AC current flow (or voltage) as a result. That portion of the resulting current flow (or voltage) that just causes energy to swish in and out of your circuit, instead of being consumed by your circuit or transmitted on to someplace else through your circuit is reactive power.

The total power that appears to be going into your circuit, it's the RMS voltage times the RMS current. Equal to real power + reactive power.

It takes energy to reverse the magnetic field in an iron inductor core. This is "iron loss"

Get a textbook...

John Popelish wrote in news:B4ydnRk1mObSyQHVnZ2dnUVZ snipped-for-privacy@comcast.com:

I don't know about the OP, but I found your explanation very clear and informative :)

Excellent.

Perhaps you would like to take a crack at substituting capacitance for inductance, current through for voltage across, and electric field for magnetic field to transform it into a similar explanation of capacitance.

Capacitors say dammit in stages: Hissing, oozing, a loud bang, lift-off.

That sounds awfully like the California state budget ;-)

Which we still don't have :-(

It's more the part of this energy that comes back out in non-electric form such as heat.

You're right--all the textbooks are wrong about all the foundations of the field. You'll have to start by banging rocks together.

Cheers,

Phil Hobbs

John Popelish wrote in news:WZudnY_KFbjmLAHVnZ2dnUVZ snipped-for-privacy@comcast.com:

Er, I just got to the section in my book dealing with Kirchoff's Law. All I know - well, what *think* I know - about Capacitance is that it's a measure of a material's ability to hold a build-up of electrons, and that, if it is near enough to a conductor, the electrons will jump to that conductor ("discharge"), so it can be used to either give a sudden burst of power (which IIRC is used in camera flash units??) or, if the power contiues flowing, to create "pulses" of power. I don't know the Math, but have in my Notebook that 1 Coulomb=1Ampere per 1 Second , and Farads=coulombs divided by Volts. ANd that the Watt rating indicates when a Capacitor will fail, so always use a Watt rating at least 2 times what your circuit's normal operation will need, just in case of a power surge.

I don't yet understand "electric field"; I haven't gotten that far yet with my self-study.

(snip)

Okay. I might get back to more effort on this thread, depending on how the O.P. responds.

snipped-for-privacy@comcast.com:

All

of

but

ates

Isn't "electric field" where sports teams from competing power companies play against each other? ;)

-Dave Pollum

Dave Pollum wrote in news: snipped-for-privacy@f36g2000hsa.googlegroups.com:

Team NPN versus Team PNP...?

Of all the googlies around here, I think I've seen a total of two come back with clarification, a thank-you, or what-have-you.

I think they think the answers will magically appear on their desk or something, albeit that totally bogus webpage would make it hard to even find the same thread, assuming they know they're supposed to come back at all!

Thanks, Rich

The homework is past due and it doesn't matter any more.

Rich Grise wrote in news:pan.2008.08.14.20.18.21.688064 @example.net:

I'd mentioned that I printed out the INductance explanation and have in my book, for when I get to that chapter, but I don't know what ever happened to the OP. I'm just slow because I'm weak in math and math-intensive sciences. But at least *some* things are sinking in, albeit slowly...

I always appreciate itwhen people take time out from their other things to supply info. Dunno about most peole, tho'; many take it for granted.

Kris Krieger wrote: (snip)

I suspect the O.P. just wanted answers that were plagiarism search proof but in copy and pastable form, and then realized that Google searches also cover this group.

Oh well.

John Popelish wrote in news:zYSdnZGcxuLMIjnVnZ2dnUVZ_r snipped-for-privacy@comcast.com:

Oh...I wouldn't have thought of that but you're probably right. It would explain the fast disappearance, tho'.

That's one thing about attending university before the advent of cut'n'paste - palgiarism was more difficult; if oyu have to hammer somethign out on a typewriter, might as well make ti something you thought of or at elast analysed on your own. Plus, plagiarism is kind of stupid, becasue even if one doesn't get caight, one learns nothing that way.

Oh wait, silly me - I still think that getting an education is supposed to involve learning... Yikes, I *am* a dinosaur!!

I thought that Iron Loss was the problem that as transformers get hot from all that current, they melt a little bit, and the iron slowly evaporates. It is a major problem in power electronics design. You either have to start with a really big, heavy transformer so that it lasts for a while, or seal it in cooling oil to contain the evaporated iron.

Of course, some of the other experts on here can elaborate on this phenomenon!

-- Charlie Edmondson Edmondson Engineering Inc

Naaaah! The iron sublimates... just like the fact content of a liberal's "mind".

...Jim Thompson