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# Skin Effect ?? How and Y?

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#### Resistance

##### Member level 4
skin effect reason

hi,

I know what skin effect is and its implications but still can anyone explain me how it actually occurs.. wats makes it occur and Y it occurs..

I would also like a few good links ..

regards.

it is a problem that surfaces when your increasing frequency of signal given to a conductor....ie once freq. is increased means it's resistance increases..
the skin effect is indirectly proportional to freq.conductivity and permeability ie skin effect depends on this 3 factors...

To get a good understanding of the skin effect,You should know about carrier recombination or relaxation time(T).
Fom the maxwells equation
DelX(H)=σE+dD/dt
Jc=σE(conduction current)
Jd=dD/dt(displacement current)
If D=D(0)exp(jωt)
then Jc/Jd=1 will yield T=ε/σ which is the relaxation time.
So for conductors where σ is large T is small and the oscillations of electrons will dampen very easily as compared to dielectrics.That is the reason why metals exihibit skin effect more than dielectrics.
I think I made my point clear.

ok ,i think i can let it simple,, if you take a cross section in the wire, and plot its magnetic flux density(using maxwell equation) , you will find that it is concentrated in the middle of the wire cross section,and smaller density at the surface,so, inductance in the bulk of the wire(in its middle)will be greater than at surface ,due to coupling of more flux,and as resistance proportional to inductance(XL=ω*L),so at high frequency ,this effect begins to appear,resulting in higher resistance at the middle rather than at surfaces.......also you can prove it using maxwell equations...

mw_rookie

### mw_rookie

Points: 2
I think skin effect surfaces from the fact that...anytime the charge withing the conductor is zero i.e. neutral...thus energy remains on the suface....now if you apply concepts of Q-mech.. i.e. recombination time etc...to complicate the situation to achieve greater accuracy then concepts of frequencies appears....

A high frequency current always try to be in surface of the conductor. It is called Skin effect.

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