skin depth

The skin effect is a phenomenon in electricity where alternating, high-frequency currents tend to concentrate near the surface of a conductor. This effect increases the conductor's resistance because the current is confined to a smaller cross-sectional area. The higher the frequency of the current, the more pronounced the skin effect becomes. This principle is utilized in induction heating, where localized heating at the surface can be controlled by adjusting the inductor coil. The skin depth, denoted by (\delta), is a measure of how far into a conductor an electromagnetic field penetrates, with a decrease in amplitude by a factor of (e) (approximately 3) occurring at this distance. At high frequencies, the skin depth is small, meaning the current is very close to the surface.12