At what frequencies is skin effect found to be greater?

Skin effect is a phenomenon in electrical engineering where alternating current (AC) tends to flow near the surface of a conductor rather than being evenly distributed throughout the cross-section. This effect becomes more pronounced at higher frequencies. As frequency increases, the depth of penetration of the current into the conductor decreases, leading to a greater concentration of current near the surface.

In practical terms, at high frequencies, the skin depth—the effective thickness of the conductor through which the current flows—increases, causing more of the current to be confined to the outer surface. This can result in increased resistance and power loss in conductors, which is particularly important in applications like radio frequency transmission and other high-speed signal transmission scenarios.

At low and medium frequencies, the skin effect is less significant, as the alternating current is able to penetrate more deeply into the conductor. Therefore, it is at high frequencies that the skin effect truly has a remarkable impact on electrical performance, making them the correct answer to the question.