Skin Depth Calculator

Skin effect is a phenomenon where alternating current (AC) tends to flow mainly near the surface of a conductor, rather than uniformly throughout its cross-section. The current density is highest at the surface and decreases exponentially toward the center of the conductor.

Skin effect is caused by eddy currents that are induced by the changing magnetic field of the AC current. These eddy currents oppose the flow of current in the interior of the conductor, forcing the current to concentrate near the surface.

Skin depth is the distance from the conductor surface at which the current density falls to approximately 37% (1/e) of its value at the surface. It represents the effective penetration depth of AC current into the conductor.

DC current has zero frequency, which means there are no changing magnetic fields to induce eddy currents. Without eddy currents, there's no force to push the current toward the surface, so DC current distributes uniformly throughout the conductor's cross-section.

Skin depth decreases as frequency increases. The relationship is inversely proportional to the square root of frequency - doubling the frequency reduces the skin depth by a factor of √2 (approximately 1.41).

Skin effect can be reduced by using multiple smaller conductors in parallel (Litz wire), using hollow conductors for high frequencies, choosing materials with lower resistivity, or operating at lower frequencies when possible.

Materials with low resistivity have smaller skin depths. Silver has the smallest skin depth, followed by copper, gold, and aluminum. However, copper is most commonly used due to its good conductivity and lower cost compared to silver and gold.

Skin effect becomes significant when the skin depth is comparable to or smaller than the conductor dimensions. For copper wire, this typically occurs at frequencies above a few kilohertz, and becomes very pronounced at radio frequencies (MHz and GHz).