The skin depth at 100kHz is approximately 0.2mm. This is based on the approximation that skin depth is roughly 66 divided by the square root of the frequency (in Hz), expressed in millimeters.
Understanding Skin Depth
Skin depth is a crucial concept in electromagnetism, particularly at higher frequencies. It describes how deeply an alternating current (AC) penetrates a conductor. Due to the skin effect, AC current tends to concentrate near the conductor's surface. The deeper you go into the conductor, the less current you find.
This effect becomes more pronounced as the frequency increases. At low frequencies (like DC), the current distributes evenly throughout the conductor. However, at high frequencies, like 100kHz, most of the current flows within a very thin layer at the surface, defined by the skin depth.
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Practical Implications: The skin depth impacts conductor design, particularly in high-frequency applications like radio frequency (RF) circuits and power transmission lines. For example, using solid conductors at high frequencies is inefficient because a significant portion of the conductor remains unused. Therefore, conductors are often made hollow or use stranded wire with a larger surface area to maximize current flow.
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Calculation: Several online calculators, like the one found on All About Circuits, allow for precise skin depth calculations based on the material's properties (conductivity and permeability) and the frequency. The formula used often involves the material's resistivity and permeability, as detailed by Pasternack's skin depth calculator (https://www.pasternack.com/t-calculator-skin-depth.aspx).
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Example: At 100kHz, as mentioned, the skin depth in a typical conductor (like copper) is around 0.2mm. This means that most of the current will be flowing within 0.2mm of the conductor's surface, while the interior carries significantly less current.
The provided references illustrate the skin effect's impact on conductor behavior at different frequencies, highlighting its significance in various engineering disciplines. The concept is deeply explored in resources like the Wikipedia article on skin effect.
