What causes skin effect in AC currents?

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SUMMARY

The skin effect in alternating current (AC) is caused by the interaction of the magnetic fields generated around the wire. Unlike direct current (DC), which distributes electrons evenly throughout the conductor, AC causes the current to primarily flow along the surface of the wire. This phenomenon occurs due to the incident magnetic field creating an opposing field that cancels much of the magnetic field entering the conductor, resulting in a concentration of current near the surface.

PREREQUISITES
  • Understanding of electromagnetic fields
  • Knowledge of alternating current (AC) principles
  • Familiarity with the concept of magnetic field loops
  • Basic knowledge of electrical conductors
NEXT STEPS
  • Research the mathematical modeling of skin effect in AC circuits
  • Explore the implications of skin effect on high-frequency transmission lines
  • Learn about the impact of skin effect on wire gauge selection
  • Investigate methods to mitigate skin effect in electrical engineering
USEFUL FOR

Electrical engineers, physicists, and students studying electromagnetism and AC circuit design will benefit from this discussion.

Qmavam
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My assumption has been it is the electromagnetic field starting from the center of the wire that pushes the electrons outward.
However, this would also be true of a DC current, but it isn't.
So why does an AC current cause electrons to move toward the skin of a wire?
I don't recall ever seeing this explained.
Thanks, Mikek
 
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Qmavam said:
So why does an AC current cause electrons to move toward the skin of a wire?
It does not.
The current starts on the outside surface, and moves slowly into the conductor.

The incident loop of magnetic field, around the wire, causes a current to flow along the wire.
That causes an opposite magnetic field loop, that cancels most of the incident field, which reduces the magnetic field entering the conductor, and so the current stays on the surface.
 

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