# Magnetic field and skin effect

1. Apr 30, 2013

In Biot savart's law we have term for current flowing through conductor. Is there any equation which describes the effects of skin effect, radius of conductor and resistance of conductor on this current with which it is possible to know the current flowing through conductor without practically measuring.

2. Apr 30, 2013

### FireStorm000

Having screwed this up myself, I can tell you not to try to use the Biot Savart law on high frequency stuff. If you look at any text on it, it will tell you that it's only valid in when the B field is not time-varying. What I believe you need is the full Maxwell's equations, as what you need can definitely be derived from those.
http://en.wikipedia.org/wiki/Maxwell_equations
Alternately, I think I've seen such an equation before; see if this page has what you're looking for:
http://en.wikipedia.org/wiki/Skin_effect

3. Apr 30, 2013

### Jano L.

What quantities do you know? You have to assume/measure something to infer the current.

FireStorm000,
for high-frequency oscillations, like in antenna, the Biot-Savart formula becomes indeed inaccurate. However, it can be accurate for time-dependent currents, provided the electric field is given accurately by the Coulomb formula (quasistationary processes, like slow capacitor discharge).