# SKIN EFFECT

At DC, current density is distributed throughout a
conductive material. As frequency increases, the depth of current density decreases.
The current density depth is called “Skin Depth”.

## Skin Depth

Skin depth is the depth, from the surface, where the current
density is equal to 1/*e* of the surface value.

*e* = Euler’s Number ≈ 2.718

## The Math to calculate the skin depth

Where:

=
Material Resistivity (Ω/m)

π = 3.14…

=
Frequency (Hz)

=
Permeability (H/m)

H = Henries
(Ω·s)