Skin Depth

A video that describes the derivation of a quantity known as Skin Depth, which is a measure of how deep that an electromagnetic wave can penetrate into a good conducting material, like for example, a metal.

[@bravomarco2419]

Perfect. No video has derived skin depth more cleanly than this video. thank you.
-from South Korea.

[@electroworld9872]

Wow, thank you!

[@paulgoyes3335]

Only one word: excellent... Thanks very much. 3AM and I am very glad so watch your video. From which book did you take all your explanation?

[@electroworld9872]

Glad it was helpful!

[@electroworld9872]

I used Daniel Frankl's Electromagnetic Theory mixed in with lots of other videos I studied about it on UA-cam.

[@matthiasweidenholzer6065]

I believe that there is a mistake at 9:37 . I think the w should be sqrt(w) on the third equation from the top. Please correct me if I am wrong. Still trying to wrap my head around the whole thing.

[@electroworld9872]

Thanks for letting me know, I'll have a look. These mistakes get through no matter how much I check these videos.

[@adamkit8983]

Awesome. Maybe you can recommend any literature on Solid State Physics? Would love to hear your recomendations.

[@electroworld9872]

I've used UA-cam to get most of my information.

[@wenwuxu6300]

Excellent derivation explanations! Thanks for sharing. If a DC current pulse (passing through a good conductor) with a climbing-up time of 500ns rising from 0 to 10000A and immediately followed by another 500ns but with constant 10000A, then dropped from 10000A to 0A within 500ns. Will the skin effect the same all this time?

[@electroworld9872]

You would have to use a Fourier Transform to calculate all of the frequencies in this pair of pulses, and they'd all have different skin depths. That's the general approach to this problem.

[@MelleLPXD]

shouldn't there be an infront the kx aswell? (in the equation for E)

[@electroworld9872]

Could you please tell me where this mistake is in the video in terms of minutes and seconds from the start, and I'll try to correct it. I just wanted to give viewers some videos on vector calculus to get them used to it, since it is very difficult for a lot of people who know algebra and calculus extremely well.

[@MelleLPXD]

@@electroworld9872 wow, didn't think you would still respond to an old video :D , e.g. 3:18 in equation (12), the whole exponent of e should be imaginary when describing sin/cos waves, thus exp(i(kx-wt)) or exp(ikx-iwt) - that's at least how I learned it

[@Titus0RA]

When you calculate the skin depth of an EM wave of 3 MHz in Iron, why do you use the permeability of free space instead of the permeability of iron?

[@electroworld9872]

The response time of any magnetic material is too slow to affect a high frequency electromagnetic wave, so the permeability of free space is the only permeability that is ever used.

[@prat_0501]

I have one doubt: electric field cannot reside into the conductor,right? That means, em waves cannot pass through conductors (because em wave has electric field components). Then how does radio signals/gamma rays pass through metals?

[@electroworld9872]

The electric field is zero inside a conductor only if it's static. If it changes very fast, then the electrons inside the material can't respond fast enough to make it zero, So it can move inside a conductor a little bit, and a lot if it oscillates at a very high frequency.

[@ayoutubechannelname]

An electrostatic charge produces a conservative electric field and can only cancel other conservative electric fields. The electrostatic screening happens almost "instantly" as the charge relaxation time constant 𝜏 = ε/σ is very small in good conductors. Thus, a conservative electric field cannot be sustained inside the conductor.
However, the electric field of the electromagnetic wave is non-conservative which can be opposed only by the electromagnetic induction due to changing currents which are present in the conducting media. This process is much slower than the electrostatic screening, and so non-conservative electric fields are easily present inside the conductor.

[@FocusStudySoundscapes]

I calculated the skin depth for a problem I am working on ~11,000 m but need to see how much the magnetic field would be reduced at 250 m.
Conditions:
sigma - 5
f - 4.166666666666667e-04
m - 1.256627e-6
Could you help point me in the correct direction? My initial thought is that 250

[@electroworld9872]

It looks like you'd use exponential functions to evaluate it, at least to evaluate the envelope exponential decaying function.

[@1jymelgar]

The derivation process is not the best, there's a mistake the expression of apha, it end with -1 and beta with +1 at 9:12

[@electroworld9872]

Thanks, I'll have a look at it. It easy to get lost in all of the vector calculus math.

[@luckyaigbovbioise1222]

thanks....great work

[@electroworld9872]

You're welcome!

[@DevendraSingh-dn2zs]

Which country you belong sir

[@electroworld9872]

I'm from Australia