![]() ![]() Increased AC resistance caused by skin effect can be mitigated by using a specialized multistrand wire called litz wire. At high frequencies, skin depth becomes much smaller. At 60 Hz in copper, skin depth is about 8.5 mm. Skin effect reduces the effective cross-section of the conductor and thus increases its effective resistance. ![]() Skin depth depends on the frequency of the alternating current as frequency increases, current flow becomes more concentrated near the surface, resulting in less skin depth. The electric current flows mainly at the skin of the conductor, between the outer surface and a level called the skin depth. It is caused by opposing eddy currents induced by the changing magnetic field resulting from the alternating current. In electromagnetism, skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the conductor. The AC frequencies used in induction cookers are much higher than standard mains frequency ‒ typically around 25–50 kHz. Induction cookers use stranded coils ( Litz wire) to reduce heating of the coil itself due to skin effect. Skin depth, δ, is defined as the depth where the current density is just 1/e (about 37%) of the value at the surface it depends on the frequency of the current and the electrical and magnetic properties of the conductor. For alternating current, current density decreases exponentially from the surface towards the inside. Distribution of current flow in a cylindrical conductor, shown in cross section. For the depth (layers) of biological/organic skin, see skin. ![]()
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