Understanding the Role of Current Density in Wire Conductors

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SUMMARY

The discussion clarifies the role of current density (J) in wire conductors, emphasizing that while DC current is distributed throughout the wire, AC current primarily exists within the skin depth region. For copper conductors at 60 Hz, this skin depth is approximately 1 cm. The skin effect significantly influences the distribution of AC current, necessitating a deeper understanding of J in this context.

PREREQUISITES
  • Understanding of current density (J) in electrical engineering
  • Knowledge of AC and DC current characteristics
  • Familiarity with the skin effect and its implications
  • Basic concepts of electrical conductivity in materials, specifically copper
NEXT STEPS
  • Research the skin effect in various materials beyond copper
  • Explore the mathematical formulas related to skin depth calculations
  • Learn about the impact of frequency on current distribution in conductors
  • Investigate practical applications of current density in electrical engineering
USEFUL FOR

Electrical engineers, physics students, and professionals involved in designing and analyzing wire conductors and their performance in AC and DC applications.

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I can see the purpose of J for currents taking place in a volume like, say.. plasma physics

but for current in a wire, it's all surface current, so why use J?
 
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Why do you think that the current is all at the surface?

For DC, it is spread across the wire.

For AC, it is mostly in the region between the surface and the skin depth. For copper and 60 Hz, this is about 1 cm.

See https://en.wikipedia.org/wiki/Skin_effect
Locate the vertical red line in the figure, or use the formulas.
 

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