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Silly guy..I said I admire your taking the effort..sheesh

CJ: ""AA is not a scientific/technical institute. It's only a techno chit-chat space despite PHP being more technically oriented as many our readers want to learn yet not technically knowlegeable enough. ""

It's much more than that. It is a hugely hostile chit chat space.

Some of the readers do understand the equations, though.

cCJ: ""For AA readers, I believe my simplified way should be adequate.""

For some, you are correct.

CJ: ""But instead of putting these complex factors to make it more complicated for our readers, technically enough or not,
to understand the sonic issue of a wire or cable, I only use "half the physics" - skip them & use insulation dielectrics, which are also valid properties of a insulated wire or cable to give another view angle for our readers.""

Neglecting the magnetic field means it is not possible to calculate the propagation speed. That distributed inductance is an absolute requirement to determination of prop speed.

CJ: ""You apply formaulae yet you don't seem to explain why & how you use them.""

I did explain. You either didn't understand, or you glossed over the explanation.

CJ: ""Let me go back to your assumption that a coaxial cable with theoretically vacuum as dielectric, will provide light speed transfer of the signal. I doubt very much despite whatever formaulae
you put forth to me.

You still fail to explain why & how these formaulae you suggested work to support your assumption.""

I told you. Work out the math.

The formula exists to determine the inductance of a coaxial cable with an inner OD and an outer ID. Calculate it for any dimension coax at all, and use an μr of 1.

Then use the formula for the calculation of the capacitance of that same coax using εr of 1.

The, use the equation V = 1/ √ (LC).

You'll find that the velocity is the speed of light.

Put it into an excel spreadsheet...then vary either the inner OD, or the outer ID..and watch the prop velocity..

It remains the same..it is invariant w/r to the size of the coax.

Then change the dielectric constant. You will find that the velocity in this coax will follow exactly the formula for free space propagation in that media.

Why you do not confirm this for yourself, I have no idea.

But the equations are there, they are real, and they work.

If you need help with the equations, just ask.

CJ: ""So how can the wave still travel at light speed as if it is a perfect zero-loss media even your assumption of vacuum dielectric stands."'

Do the math..it works.

And, it is verifiable. It is (and has been)easily confirmed using tdr.

CJ: ""This is only logics, I don't care what formulae you use.""

That you don't care about the formula is something you've made quite clear. However, it is inaccurate and illogical to ignore 6 decades of e/m theory and it's results. That is what you are doing here. It is unfortunate that you choose to not let the facts get in your way.

As I said...I can only show you the door..your refusal to go through it is your issue, not mine.

Cheers, John

PS..obviously you need a lot of help here. (Your welcome)
Here's the simple equation, maybe you'll try it??

Prop delay of a coax:Note: The equation has also been simplified for the reader, the removal of μ in this equation means it is only applicable for media with free space permeability..and it only applies to a coax. Changing the geometry, such as offsetting the center conductor or going with parallel wires or ribbons means this equation is useless.

B = 84.72 * 10-12 √ εr seconds per inch.

Now, Speed of light is 299792458 meters per second

there are 39.3700787 inches per meter.

Multiply SOL by inches per meter, you get:11802852665.1264446 inches per second. Now, invert that to get to the units of the prop delay from the previous equation...

1/11802852665.1264446 =..ta da..84.725280266750 * 10-12seconds per inch.

Now, you could try calculating the inductance and capacitance, then the prop velocity, as I suggested (and you ignored).

L = length(inches) * 5.08 * 10-9 ln(outer ID/inner OD)

C = length(inches) * 1.41 * 10-12/( ln(outer ID/inner OD))

You know the prop velocity equation..



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  • Silly guy..I said I admire your taking the effort..sheesh - jneutron 13:39:27 04/05/06 (0)
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