Skin Definition and 152 Threads

Hi, I have a very oily skin especially in the face and hair. I think the oil causes acnes or something called foliculit. Foliculits and oil started at the end of the secondary schools which corresponds to puberty. I used a tablet it was good for me. It dried my skin against oil but it dried...

I'm struggling to understand a key detail about this. My book divides the cross section of a wire into elementary filaments. It then states that the flux linked by the filament in the centre of the wire will be greatest, then this will decrease until at the outermost filaments the only flux...

I have found from various sources that the emissivity of human skin, irrespective of pigment, is close to unity. I am also unsure as to why ice has such a high emissivity too- perhaps my understanding of emissivity is fundamentally flawed! Any help or guidance on this topic would be...

As we know due to skin depth effect the Alternating Current flows at a depth from the conductor surface (which means there is no voltage on the surface of the conductor, it is only at a depth from the surface). Then how is it possible for voltage to get appeared across some other conductor...

I recently started working in low voltage electrical repair/upgrades in automobiles. I have a couple interns that i am working with and i truly want to be dam* sure I am explaining things properly to them. Me and my boss have had heated discussions on the subject and i believe him to be...

Wikipedia suggests a typical human has ~ one trillion bacteria on their skin. That’s orders of magnitude more than a cell phone and many many orders of magnitude more than a toilet seat. They typically don't cause disease and may offer benefits. It kind of bothers me that there’s this common...

I am collecting skin conductance data for a research study. For this, we apply a constant voltage (5v) to a participants finger and then measure the voltage at another finger (or I think this is what is happening, there is also something about a resistor in there [see attached schematic])...

This is driving me crazy. The derivation of the current distribution in a long cylindrical wire is extremely straightforward, giving J(r) = J(a) \frac{J_0(k r)}{J_0(k a)} where J is the current density, a is the radius of the wire, and k is the complex wave vector, which in a metal (with...

Hi all The reflection and transmission of a pressure wave at a boundary depends on the relative impedance of the two media. I'm pretty new to acoustics but the textbook I've been looking at doesn't seem to specify that the such calculations are only valid when the medium is at least a few...

Today, I was thinking about skin burns after climbing some poles in the park and was wondering this: I understand that a frictional force is determined with the equation F = μN = μmg. However, it is also to my understanding that when you drag something on your body across a surface, let's...

In Biot savart's law we have term for current flowing through conductor. Is there any equation which describes the effects of skin effect, radius of conductor and resistance of conductor on this current with which it is possible to know the current flowing through conductor without practically...

Homework Statement I have attached the photo of the circuit. My doubt in the circuit is that, I could not exactly figure out what the diodes do. The description says it is used to set the input of the op-amp to 1.6V above v-. But how exactly does it achieve that? Can somebody show it...

I have to thinking about how the skin effect come into play in transmission lines with two conductors and dielectric in the middle. For normal skin effect, we consider a potential across a conductor as shown: Where the tangential E right above and right below the surface at z=0, are...

Can anyone out there tell me why a voltmeter would strongly register when I touch it to my arm, and yet I am in no contact with any electrical current? This seems outrageous to me. It is a commercially available pen tester bought at Home Depot and set on the highest setting.

Hi. I'm trying to understand why smaller skin depths are better for induction heating. Skin effect means that the highest the frequency is, the thinest the skin depth is (or the depth is simply smaller because of the material). That means the section of the workpiece with electric current in...

Can someone please explain in a detailed manner about skin effect in electromagnetism, particularly wanted to know why does this effect take place??

Hey I know the conclusion of skin effect since secondary year of school, but I still didnt get it. I know the reason is because of eddy current. I couldn't include the link here as I haven't posted 10 yet. For the link, just search "Skin Effect" at Wikipedia. First paragraph of the cause in...

Three substances of nickel, chromium and cobalt, lead to dermatitis ratio accounted for 25 substances, the first, third and fourth place. Does anyone have any suggestions on what kind of reactions between metal and sensitivity skin? Thanks in advance for any suggestions

Hey All, Im creating this thread to share some of the information, and hopefully gain some information on dual skin walls. Dual skin walls are a fairly new advancement in facade design in North America, however they are more common in Europe. The first dual skin facade in North America...

Let's say we have 2 different conductors - one a round wire, another a round wire but with hollow core. The wire with the hollow core has higher resistance. But for the sake of argument, let's assume that it has the same resistance and the round wire. Will the skin effect be less for the...

Okay before I proceed, imagine the following kind of omlet. So you have a thin la year of egg with small pieces of green pepper and onion. Also green pepper lost some of its color so its ''light green'', and likewise onion is a bit transparant as opposed to white. Now imagine that it is not the...

I need to Calculate the Skin Effect of water in a tube of X Diameter or Surface Area... The length of the Flow in the pipe would be 200 mm. I know that is short but it matters in this instance. The pressure of the water would be around 15 bar. I will post the flow rate through the pipe as soon...

I recently went to a "party" where the host was offering skin care products to buy. In order to figure out what you need you were advised to use this SAM or Skin Analysis Machine. It looked like a football replay box. You put your head under a cover and looked into this mirror. A black light...

Can anyone please describe the reason behind skin effect? All that I have come to know so far is that, due to higher magnetic flux density at the central region of the conductor compared to the region near it's surface, the effective inductance of the conductor is more at its centre and less...

Hi all, I want to resonantly charge a capacitor, i.e. using a coil and diode combination instead of a resistor, in a very short period, which means a high current at high frequency. The problem is the coil. I read that at high frequency AC you get to deal with the skin effect, and also the...

I've been looking into the induction heating a bit lately and have come up with a few questions. One is in regards to hysteresis losses. I know what hysteresis is and how it contributes to the heat generation, but how much of an effect does it actually have? Some articles I've read have...

Is there anything to support that drinking more water improves dry skin remarkably?

I know this is a well known skin disinfectant, but my note say iodine is inactivated by organic matter. Isn't skin organic matter, so how does this work. Thanks :smile:

Homework Statement for my assignment given i was told to derive the equation of the skin depth of a good conductor and i derived it as d=sqrt(2/\mu\omega\sigma) then i was told to calculate d where i was given w=10^15 and sigma=10^7 and this gave me a d of d=1.26E-8 which i guess is...

I had issues with dandruff for a long time. Once my second kid was born, I went two weeks without a shower. My dandruff basically went away. Since then I've been showering with water only. My hair has become way healthier and my skin is all a consistent color and doesn't get scraped and...

I'm trying to calculate skin friction drag on a truck so I can compare it to pressure drag. I can find the formula and typical coefficients for pressure drag easily enough but I've had a hard time finding it for skin friction. So far I've found this...

Hi! I need some help with the following - I have a square oven that has an outer shell of stainless steel (10mm thick) that has a skin temperature of 180degC. Outer shell size of each side is 800mm x 800mm. This has to be water cooled to bring down the skin temperature to 50degC. We need to...

What is scientific reason behind skin effect of conductors?

Homework Statement "The probability that a new drug will cure a skin rash is 0.82. if the drug is administered to 200 patients with the skin rash, find the probability that: a)more than 150 will be cured? b)between 170 and 180, inclusive will be cured? " Homework Equations The Attempt at a...

Hello Forum, the formula for skin depth is both inversely proportional to conductivity and frequency omega. There seem to be 3 cases when the skin depth of a metal is exactly (or tends to) zero: 1) if an EM wave of frequency f (any frequency) is incident on a perfect metal wall (infinite...

Dear all I am slightly confused over the equations for skin depth. My university notes give me the equations: \delta = tan-1 (tan\delta) = \frac{\sigma}{\omega \epsilon} (loss tangent) where \delta is skin depth and \sigma is conductivity. I am also given the equation: \delta =...

Amazing new tech! https://www.youtube.com/watch?v=7Y5H9Sasq5U [/PLAIN]

I want to verify my understanding about skin effect and plane wave of conductor wire. In the diagram, assume long straight on z axis. Wire with radius = a and conductance = \sigma . Accouding to the equation shown, the plane wave is going towards the center of the wire only...

In the field of microwave engineering, skin effect is referred to when people talk about the fact that current, that is, electrons only flows on the surface of transmission lines, e.g. microstrip lines. I've checked many EM books--everywhere skin effect is demonstrated with both E and H...

why people living in cold weather are white in colour?? and that of in hot weather are black in colour? lyk European american etc are white and african are black in colour

Is the only reason air moving over your body caused by a fan or breeze feels cool because of increased evaporation of moisture from your skin? Or does it blow air being warmed by your skin away from your body to be replaced with relatively cooler air? Also, does air movement also produce...

Most places I've read say it's because the car forms a Faraday cage, but a few say that is incorrect and that it's actually from the skin effect. The notable case of the latter explanation is from the Boston Museum of Science: http://www.mos.org/sln/toe/cage.html This guy, Dr. Davis from the...

In DC circuits the charge carriers move uniformly through the entire cross sectional area of the wire. In AC circuits the current is constrained to travel in a thin "skin" just below the surface of the wire, effectively reducing the cross-sectional area of the wire. The effect becomes more...

Can lipids/triglycerides/fats be absorbed through the skin? I know the skin is waterproof but is it fatproof? Can fat be absorbed through the skin and increase the subcutaneous fat layer? Specifically butter, olive oil, is there a difference between saturated and unsaturated fats? I'm just...

I was wondering if any values for this were ever recorded. How strong is human skin when subjected to pressure? Since there are figures for steel which constitutes classical armor and values for bullet proof vests, I wanted to work out what magnitude of protection those things give you against...

http://www.elastoplast.com.au/media/11/12276804863360/schnittwunde_03.jpg If your skin is cut deeply, meaning a cut to dermis why is that we can see scar tissue. I mean if the cut region in the dermis would be replace by scar tissue, but the epidermis region above that would have normal...

References are available to calculate skin effect, RAC/RDC given wire gauge and frequency. But my problem is a complication of this simple calculation. Say I have a 1 Amp RMS AC current component and a selected wire size that gives me a skin effect of 7X the DC resistance. But I also have a...

Does skin that is perpendicular to the sun’s rays burns faster than skin that is closer to parallel to the sun’s rays? I was certain that it does but a very smart friend/engineer is certain that it doesn’t and was incredulous that I thought it did. I really would like to know the physics...

Hi All, I know that the environment is responsible for people of African descent having black skin and people of Scandinavian descent have white skin but I cannot figure out the logic behind this. I thought it had to do with the absorption of Vitamin D from the sun and the Scandinavian...

Hi all! This is my first post :D I came across skin effect which blocks propagation of an em-wave within a conductor... But doesn't the energy generated at an electric plant reach our house through conductors flowing for over a 1000 miles sometimes? If I have to consider it just as an...