# What is scientific reason behind skin effect of conductors?

What is scientific reason behind skin effect of conductors?

## Answers and Replies

berkeman
Mentor
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?

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?