What phenomenon causes AC currents to flow near the surface of a conductor?

What phenomenon causes AC currents to flow near the surface of a conductor?

• A. Skin effect
• B. Ground effect
• C. Skin depth
• D. Surface current

Answer: (A)

The phenomenon that causes alternating current (AC) to flow primarily near the surface of a conductor is known as the skin effect. As AC flows through a conductor, the distribution of the current density is not uniform throughout the entire cross-section of the conductor; instead, it decreases with depth from the surface. This effect arises because of the electromagnetic induction and the associated self-inductance of the conductor. When AC is applied, the changing magnetic field generated by the current induces eddy currents in the conductor, which oppose the change in current due to Lenz's Law. As the frequency of the alternating current increases, the current flows more densely near the surface and less in the interior of the conductor. This concentration of current near the conductor’s surface reduces effective cross-sectional area for current flow, resulting in increased resistance and losses. Understanding skin effect is crucial in engineering applications, particularly in power distribution and high-frequency signal transmission, as it influences conductor sizing, losses, and heating in electrical systems.

The phenomenon that causes alternating current (AC) to flow primarily near the surface of a conductor is known as the skin effect. As AC flows through a conductor, the distribution of the current density is not uniform throughout the entire cross-section of the conductor; instead, it decreases with depth from the surface. This effect arises because of the electromagnetic induction and the associated self-inductance of the conductor.

When AC is applied, the changing magnetic field generated by the current induces eddy currents in the conductor, which oppose the change in current due to Lenz's Law. As the frequency of the alternating current increases, the current flows more densely near the surface and less in the interior of the conductor. This concentration of current near the conductor’s surface reduces effective cross-sectional area for current flow, resulting in increased resistance and losses.

Understanding skin effect is crucial in engineering applications, particularly in power distribution and high-frequency signal transmission, as it influences conductor sizing, losses, and heating in electrical systems.