What is the phenomenon where AC currents tend to flow near the surface of a conductor called?

The phenomenon where AC currents tend to flow near the surface of a conductor is called the skin effect. As the frequency of the alternating current increases, the distribution of the current density within the conductor becomes non-uniform, leading to most of the current flowing near the surface rather than throughout the entire cross-section. This happens because the changing magnetic fields associated with the alternating current induce eddy currents that create additional opposition to the current flow in the interior of the conductor.

The skin effect is significant in applications involving high frequencies, such as RF communications, where the effective resistance of the conductor increases due to this concentration of current at the surface. This can lead to challenges like increased heat generation and power loss in conductors. Understanding this effect is essential for designing efficient electrical systems and selecting appropriate conductor sizes and materials for specific applications.

In contrast, other options relate to different concepts in electrical engineering: surface loss typically refers to energy loss at the interface between materials, inductive coupling involves the transfer of energy between two coils through a magnetic field, and capacitive coupling deals with the transfer of energy between two conductive elements through an electric field. Each of these phenomena serves distinct purposes and operates under different principles compared to the skin effect.