What is scientific reason behind skin effect of conductors?

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Discussion Overview

The discussion centers around the scientific reasoning behind the skin effect in conductors, particularly in the context of alternating current (AC). Participants explore the mathematical representation of current density and its exponential decay with depth, as well as implications for inductance and resistance.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants describe the skin effect as the phenomenon where AC current density decreases exponentially from the surface of a conductor, with a defined skin depth δ at which the current density falls to 1/e of its surface value.
  • Equations related to skin depth are presented, involving resistivity, angular frequency, and magnetic permeability, though questions arise about the derivation of these equations.
  • One participant questions the relationship between inductance and current, noting that while inductance increases and current decreases, the AC resistance is calculated as Rac = 1.6 * Rdc, prompting inquiries about the power factor.

Areas of Agreement / Disagreement

Participants express differing views on the implications of inductance and resistance in relation to the skin effect, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

The discussion includes unresolved questions about the derivation of equations related to skin depth and the relationship between inductance and AC resistance, highlighting potential gaps in assumptions or definitions.

djsourabh
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What is scientific reason behind skin effect of conductors?
 
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djsourabh said:
What is scientific reason behind skin effect of conductors?

Let us know if you still have specific questions after reading this introductory article:

http://en.wikipedia.org/wiki/Skin_effect

.
 
The AC current density J in a conductor decreases exponentially from its value at the surface JS according to the depth d from the surface, as follows:

where δ is called the skin depth. The skin depth is thus defined as the depth below the surface of the conductor at which the current density has fallen to 1/e (about 0.37) of JS. In normal cases it is well approximated as:
.
where
ρ = resistivity of the conductor
ω = angular frequency of current = 2π × frequency
μ = absolute magnetic permeability of the conductor

courtesy from wikipedia
how these equations came from?
 
berkeman said:
Let us know if you still have specific questions after reading this introductory article:

http://en.wikipedia.org/wiki/Skin_effect

.

The AC current density J in a conductor decreases exponentially from its value at the surface JS according to the depth d from the surface, as follows:

where δ is called the skin depth. The skin depth is thus defined as the depth below the surface of the conductor at which the current density has fallen to 1/e (about 0.37) of JS. In normal cases it is well approximated as:
.
where
ρ = resistivity of the conductor
ω = angular frequency of current = 2π × frequency
μ = absolute magnetic permeability of the conductor

courtesy from wikipedia
how these equations came from?
 
But actually the inductance L increases hence current decreases,
then why the ac 'resistance' is calculated as
Rac =1.6*Rdc ?
&
what happens to the power factor?
 

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