What is Permiability and Permitivity of Vacuum

Hello, dhayanandhan,

Mind if I take a stab at this? (Possibly it will spur further discussion by more knowledgeable members?)

Look at the units of both constants. Permeability is in units of Henries/metre and Permittivity in Farads/metre. Now think about what sort of units are Henries and Farads, particularly how they're defined. For the sake of brevity allow me to pick on my personal favourite, Farads: C = i dV/dt (F), per metre. This sort of suggests (to me at any rate) that both constants refer to the Vacuum's intrinsic ability to store energy in the form of magnetic and electric fields, respectively, per unit length.

Or, more to the point, how they're used in Maxwell's equations, where they first showed up, measures of the degree to which the Vacuum opposes changes to same per unit length, given that both constants fix the propagation velocity of electromagnetic waves through the Vacuum. Look at what effect hypothetically changing these values would have on the speed of light. Note that these two constants also determine the impedance of free space, fixing it at about 300 ohms, more or less. What is this impedance caused by? How fast you move electromagnetic energy through space, possibly? The slower the speed of light, the higher the impedance (the root word is 'impede,' after all). Of course this could all be bogus, so you'd better check me on this!

Night Owl

Dear Mr.Night Owl,

Thank you for your posting. Indeed, you rightly mentioned "it will spur further discussion by more knowledgeable members?

My contention is "Let us wait."

DHAYANANDHAN.S

Thanks! Sounds like a plan. :)

Google finds the correct pages either way.

Sure does, want me to put it in harder words for OP then?

Quite honestly, I would much rather you replied to him in his native tongue as graciously as he replied to you in yours.

You mistake me for something I am not.

My native tongue is us much English as yours is French or Dahal.

I see you have not been around much here. Keep watching for the good posts where things that can easily be googled get a much more drastic response.

I wanted to, and I hope I was, reply in a friendly and nice manner. Sorry if this did not read as such for you.

I have 'been here' for quite some time, actually, as a reader only. Several years, in fact. I've also read the site's FAQ and its exhortation to English speakers to graciously accommodate those whose native tongue may not be English but some other language. This group comprises most of CR4's members and with whom I also identify. In this light, I feel that your reply to the OP could have been far more accommodating. I daresay that if your roles were reversed, you would have fared far worse posting your query in Hindi, spelling-wise, but that he would still have responded to you with at least as much grace and consideration as he responded to you here, in your own tongue. You can be a gentleman in any language - or not. The choice is yours, as always.

Put it that way, I was as accomodating as I couldbe, being English not my native language. I wanted it to sound nice and I am convinced compared to some other daring responses it was rather well put. I wonder why you ponder your point. Using the word "miss spelling" seem to induce in you the notion that it was a rather mean reply while it was meant helpfull. If you cannot see this then maybe it because "my English very bad" or your intent is somewhat screwed, which I dont want to go into.

Knock it off if you want to be as graceful as you ask of others.

Thank you Mr.IdeaSmith,

Thank you for your posting.

I have copied the word and pasted, so as to know from CR4 MEMBERS.

DHAYANANDHAN.S

As far as I remember, they are derived from Maxwell's equations, and treated as standards. Other than that, what is the problem?

Dear Mr.leveles,

The VACCUUM is a MECHANICAL or PHYSICAL matter or aspect.

The PERMIABILITY and PERMITTIVITY is a DIFFERENT matter or aspect - and mainly related to Electrical Subject.

First time, I am coming across "PERMIABILITY and PERMITTIVITY of VACCUUM"

How are they related, and any Variation, HOW it affects on Mechanical Side or Elec.Side.? is my question.

I request CR4 MEMBERS to enlighten this matter.

DHAYANANDHAN.S

Now, that you defined yourself clear enough with your last statements, allow me to propose some books I enyoyed greatly on the matter.

Michael Faraday: Experimental researches in electricity/

ISBN 0-486-43505-9

Michael Faraday: Experimental Researches in Electricity

No ISBN yet, London, Bernard Quaritch, 15 Picadilly, 1844

3 or 4 volumes from the top of my head.

You will find these valuable volumes in any qualifying

libraries.

I wish you good luck with the studies.

best regards

Leveles

I have slept on my note, and here is an extension of two totally different path. Start with Amazon.com.

Max Planck was a physicist of a top rank in the classical school. He had great difficulty to produce the theoretical underpinnings to the "black body" heat radiation. Then he was the first to introduce the quantum of energy, that solved the problem, and earned him a Nobel prize. After that, he spent some 5 years to prove to himself, that a classical solution was not possible.

Then there is Michio Kaku, a professor of particle physics in New York. He likes to popularize many things. He wrote a small book some 20 years ago on the strict mathematical underpinning in tensor form, of all the physical world. Stripping a row or column from it yields among others a complete Maxwellian theory, constants and all. I personally do not like that purist mathematical approach, because that depends on me trusting his premises, most of which I do not know what they are. An accomplished particle physicist may know them, but I am not there. With this caveats he is a good read, and makes plenty of sense. If you are mathematically inclined, that is.

To me all the above proves, that such constants (and many others) are part of the theories. And experiments provide them with greater and greater precision. I have yet to see a theory explaining why constants are needed, as they are.

Well said! GA.

Might add that 1/√(μ₀*ε₀) = c.

Check this out:

http://www.thenakedscientists.com/forum/index.php?topic=43681.0

Permittivity, think of the units this way, Farads per sq metre per metre, F/m*m/m

Compare with the formula for the capacity of a flat plate capacitor C= eA/d where

units of A are sq metres, and units of d are metres.

Permeability I haven't worked out, sorry.

Read Steinmetz.

i only do the digit resequencings (something we can call mathematics)

from:: modified : 2002-05-24

i donno much about thissh¡t (the values are not up to todays date)

derived ...

µ_o = 4π x 10 ^-7 (H/m)

ε_o = ( c² x µ_o ) ^-1 (F/m)

Fm^-1 = C(Vm)^-1 = C²(Jm)^-1 = C²(Nm²)^-1 = C²s²(kgm³)^-1
Hm^-1 = Vs(Am)^-1 = Vs²(Cm)^-1 = Js²(C²m)^-1 = kgm²(C²m)^{-1
hope i didn't messed it up here}

By now, the math is impressive, and at times dizzying.

Nonetheless, BY NECESSITY IT IS CIRCULAR.

They are tightly tied to c. no choice.

The value and dimension is determined, what the theory needs.

It is too bad, that I cannot be more accomodating. This is, what it is,

and no desire changes that.

This is circular math. Did you mean to say that God used circular logic when he created the universe?

i know you guys not gonna like next but let's try it that way ... each time the nuke scientist came out with another collision the particle(((s))) interpreted their apparence according to available energies and conservation laws ... what if there is no need to create universe over demand e.g. accomodate the events that lokely never occur

the resolving logic is ... i don't remember that stuff right -- to manipulate the system you have to be the system.partOf() as (/!\bad excample follows/!\) to process 1+1 you are the 1 replicating yourself would violate the laws of conservation so the only way (◄◄/!\) to do it would be be a=1×α and b=1×ß and to stay in sys C=a-b ... let's chk our whereabouts ... D=a+b=2a-C=C+2b def.Zero("="±(2C-2C))=[since previous is a violation](=±(C(a-b)-C(a-b))=[spsav]=... there must be remnant outside the sys that'd enable pullback and the def.Zero here without violations ...)

???

Can anybody explain what he's rambling about?

it's like origami - you got blank sheet of paper and you got to get everything eout of it

if you are that sheet you possibly wont know the meaning of 2 nor 1 as such are relative to each others excistance

the simple way is to falsify time

the simple way to see the falsified time is to analyse stereoscopic vision - for spirit these are two windows to inner-space ... such as which i is more i (eye)

+ is there a time or willing to track the course of events in your mind e.g. constantly keep creating the time in your mind and keep your attention offset to future

(far past memory:) if you go to 4/5D mode then what you see instead of what you saw in 3/4D mode is like zoom out with DCam ... more "space" it's like looking through simple binoculars the way around the usual ... and the objects are like projected here from far off - you can enter that projection path and reach the object far far off from here - to not get confused by prev. it's like you zoom in from here to there (a vision flight) but also you can "lock into" the "target" and stay focused to no matter what's going around in here and proximity

one translation is that far is disant in real time , and there is no movement in space , but the time change/travel only e.g. for gong to "point" A from "point" B requires re-relating your manifestation in time/(the whole system that is parametrisized by) and that change is falsified by your mind to you as a movement in space - simple - i personally dont get a sh¡t of it - just remember alike stuff - every now and then in connection to some sound thought movie image sensation

less is more read the first line only

i stole that from wiki

i stole that from wiki too

so ... whats the constant of gravitation
just a scalar dimensioning F in the above instance as ε_o μ_{o below}

the question in closed systems is usally what (is that) you don't see (here) ... here . . . h e r e ? ? ? (&%"(&)"/&"=( random data . . . (just perhaps)

Hi,me

nothing to do ...

http://rspa.royalsocietypublishing.org/content/early/2012/09/25/rspa.2012.0340.abstract -- havn't been reding physics news for a while

http://physics.nist.gov/cuu/Constants/Table/allascii.txt -- from where:

speed of light in vacuum ◄► 299 792 458 ◄► (exact) ◄► m s^-1
Newtonian constant of gravitation ◄► 6.673 84 e-11 ◄► 0.000 80 e-11 ◄► m^3 kg^-1 s^-2

1/(cG)=49.980834901368934462854475755325

[1/(cG)]=(kg/m³)/(m/s³)=(kg/m)/(m/s)³ ...

... i've written here (**was missing 1/)cG=1/(π/2-arctan(1/(cG))) -- it might be just a random test not a deterministic deduction ... random chk follows ** . . . it's likely random test

Bye,me

Take Coulomb's law (below) and vary the value of the vacuum permittivity

.

Since the vacuum permittivity is in the denominator, you can see that if you increase it's value the electric field is weaker for a given charge. Conversely if you decrease the the vacuum permittivity, the electric field is stronger for a given charge.

For the vacuum permeability, we can use Biot-Savart Law to gain insight:

Notice the vacuum permeability is in the numerator. So if you increase the vacuum permeability, you get a larger magnetic field for a given current and conversely if you decrease it you get a smaller magnetic field for a given current.

So as the permittivity is to the electric field, the inverse of the permeability is to the magnetic field (or vice-versa). Both describe how effectively their associated fields "spread out" from a source.

Finally some insight can be gained by examining the Permittivity and Permeability with respect to the speed of light in a vacuum.

.

Clearly an increase in either of these constants would result in a slower speed of light. Light is simply an electromagnetic wave propagating through space. On a string, the speed of a wave can be reduced by reducing the tension of the string (which reduces the effort required to displace the string) or by increasing the linear density of the string (which essentially makes it heavier, more inertial).

Recalling that the Vacuum Permittivity is to the Electric Field as the inverse of the vacuum permeability is to the Magnetic Field, one can note by comparison that these vacuum constants describe the speed of light in a way similar to how Tension and Linear Density describe the speed of a wave on a string. Is this analogy physically meaningful? Not in any obvious way. However thinking of the constants in this way can provide some intuition as to their meaning.

Best Regards,
Roger

Hi Roger,

Glad to have you back. This post was very readable compared to some others. Thanks

-S

Hi Mr. S.G. your post was very short and discreet as in fact it didn't revealed much anything - compared to some others i wonder how old are you - i mean you live and learn that in a world with 8E9 population there are only americans with higger than average education and that think the way you do or liked to ... this is soo cool blwuah wlawh wlawlah

not getting into subject ... yet ? "old timers" ... ? how old timers

a better picture