Skin Depth
\delta = \sqrt{ 2 \rho / \omega \mu_r \mu_0 } in m ~=~ \sqrt{ 2.533e11 \rho / f \mu_r } ~~ in mm ~~~~~~ 2 / 2 \pi \mu_0 = 253303 m/H
Material |
Temp |
perm. |
resis. |
depth (mm) at frequency |
||||||
|
K |
\mu_r |
\rho~~\Omega-m |
1 Hz |
60 Hz |
400 Hz |
1 KHz |
5 KHz |
20 KHz |
200 KHz |
3% Si Transformer Steel |
300 |
700 |
5e-7 |
13.4 |
1.7 |
0.67 |
0.43 |
0.19 |
0.95 |
0.030 |
3% Si Transformer Steel |
600 |
300? |
7e-7? |
24.3 |
3.1 |
1.2 |
0.77 |
0.34 |
0.17 |
0.054 |
Copper |
300 |
1 |
1.7e-8 |
65.6 |
8.5 |
3.3 |
2.1 |
0.93 |
0.46 |
0.15 |
Copper |
600 |
1 |
3.8e-8 |
98.1 |
13 |
4.9 |
3.1 |
1.4 |
0.69 |
0.22 |
Aluminum |
300 |
1 |
2.8e-8 |
84.2 |
11 |
4.2 |
2.7 |
1.2 |
0.60 |
0.19 |
Aluminum |
600 |
1 |
5.9e-8 |
122.2 |
16 |
6.1 |
3.9 |
1.7 |
0.86 |
0.27 |
Resistivity - for copper see Matula 1979 page 1161, for aluminum see Simmons 1960