resistanceskin-effect
I have 4 cylindrical conductors spaced equally and horizontally apart. How can I calculate the magnitude of Impedance (Z) using the Skin effect and Proximity effect?
I'm looking for an equation that will output Z given things such as the cross sectional area, length, frequency, and physical constants.
The skin effect is the effective reduction in the cross sectional area of a conductor that carries high frequency AC. The current density is higher on the outside of the conductor than it is an the inside. The actual resistivity of the conductor is still uniform throughout.
Its essentially an example of back emf which is strongest in the middle of the wire produced by the changing magnetic field of the AC.
The skin effect is an effect of frequency.
At DC there is no skin effect so the resistance is a function of the cross section of the conductor.
As frequency rises, the current tends to decrease at the center of the conductor as you said. For the current to flow only at the surface of the conductor, the frequency of the current should be infinite. In reality there is always current flow with diverse density at different depths of the conductor, but there is never current "only on the surface".
Best Answer
There is no one answer; you need to consider each possible pairing of wires individually. With symmetry, there are four unique cases. The formula can be found here.