Talk:Skin effect

message: Prior content in this article duplicated one or more previously published sources. The material was copied from: https://faculty.mu.edu.sa/aabokhalil/Skin%20effect https://onebyzeroelectronics.blogspot.com/2015/05/what-is-skin-effect-phenomena-arising.html. Copied or closely paraphrased material has been rewritten or removed and must not be restored, unless it is duly released under a compatible license. (For more information, please see "using copyrighted works from others" if you are not the copyright holder of this material, or "donating copyrighted materials" if you are.)
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replies: text: That text has been the same since at least 2012.  Is it possible that those sources copied Wikipedia?Constant314 (talk) 02:31, 27 June 2019 (UTC)

text: The mu.edu site has a copyright of 2019.  The nebyzeroelectronics article was published in 2015.  It looks like they copied Wikipedia. Constant314 (talk) 03:24, 27 June 2019 (UTC)
thread_title:  Copyright problem removed 

message: There is a statement about the skin depth in silicon not being less than about 11m.  This statement does not have a reliable source and I believe that it is incorrect, so I will remove it.
There does not need to be any justification other than there is no reliable source cited, but I will give a more elaborate justification.  
The formula, as given, is correct if you can neglect dielectric loss.  Any type of loss will decrease skin depth.  Using  these equations from wavenumber:
: \delta = \frac 1 {k}  
:k = k' - jk = \sqrt{- j \omega \mu (\sigma + j \omega \epsilon)} =\sqrt{-(\omega \mu  + j \omega \mu ')(\sigma + \omega \epsilon  + j \omega \epsilon  ') }\; ,
In the equation for wavenumber, you see \sigma + \omega \epsilon  .  The dielectric loss term  ands to the conductivity term.  This effectively reduces resistivity as frequency increases.  It is straight forward, but tedious, to carry out all the multiplications, gather terms, and apply the formula for the square root of a complex numbers.  The result shows that if there is any dielectric (or magnetic) loss, then there is no non-zero lower bound.  If someone would like to check the math, I would be grateful.
I plugged numbers in, assuming a dielectric loss tangent of 0.3% at 10GHz I got 0.9m at 10GHz.  The conclusion that skin depth in silicon is deep enough to ignore is still correct.  Of course, I could have made a mistake.  If anyone would like to run the numbers, I used   {\epsilon } / {\epsilon '} = 0.003 , \epsilon_r=12, \sigma = 435 \mu \; \mathrm{ S/m } Constant314 (talk) 23:52, 21 February 2021 (UTC)
thread_title:  Lower bound for skin depth in silicon 

message: Hi, first contribution here
I think the graph labeled as "Current_Density_in_Round_Wire_for_Variuos_Skin_Depths" is wrong, or maybe I don't understand the scale.
If the number labeled on each curve is skin_depth/wire_radius, let's consider a 1.0 ratio (which is not showed here), then, at the center of the wire, current density shhould be 1/e (~0.37) of Js (current density at surface). And so, at <1 ratio, value at should then be <1/e. However, curves seem to show a value way higher (~0.95 just for 0.9 ratio curve), considering a linear Y scale. WaldenoffFR (talk) 21:14, 11 March 2023 (UTC)
replies: text: I drew the graph.  It is correct; it is simply the evaluation of the equation given in that section.  The relation that you are thinking about only holds when skin depth is small with respect to the radius of the wire. Constant314 (talk) 22:34, 11 March 2023 (UTC)
thread_title:  Current density graph