The solid conductor considered can be thought of having a number of strands one over the other, each carrying some portion of the current, so the inductance of the each stand will be vary and will increase towards the center. The high reactance of the strands near the center will increase the tendency of the current to flow with greater density near the outer stands. This result in a more power loss for a given r.m.s value of current, or the effective resistance is increased, also skin effect decreases the effective internal reactance. According to Maxwell and Rayleigh, the ratios of skin-effect resistance to direct current resistance and the skin-effect reactance to direct current reactance are given as:
Hence the skin effect resistance and reactance depend upon frequency. For high-frequency currents, the skin effect predominates. The above formulae are not much used practically. For practical purpose the value of
The empirical formula for
The Skin effect depends upon the following factors: