Understanding the Role of Current Density in Wire Conductors

AI Thread Summary
Current density (J) is relevant in wire conductors as it helps understand how current distributes within the wire, particularly for AC and DC applications. For DC, current is distributed throughout the wire, while for AC, it primarily resides within the skin depth, which is about 1 cm for copper at 60 Hz. The skin effect causes current to concentrate near the surface, leading to a non-uniform distribution. This understanding is crucial for applications in fields like plasma physics and electrical engineering. The discussion emphasizes the importance of J in analyzing current behavior in conductors.
iScience
Messages
466
Reaction score
5
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?
 
Physics news on Phys.org
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.
 
Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'

Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'

So here is the motional EMF formula. Now I understand the standard Faraday paradox that an axis symmetric field source (like a speaker motor ring magnet) has a magnetic field that is frame invariant under rotation around axis of symmetry. The field is static whether you rotate the magnet or not. So far so good. What puzzles me is this , there is a term average magnetic flux or "azimuthal mean" , this term describes the average magnetic field through the area swept by the rotating Faraday...
View full post »

Similar threads

A Relationship between magnetic potential and current density in Maxwell
Replies
2
Views
2K
A A question about current density in finite element analysis
Replies
2
Views
1K
I Ampere's Law For Static Magnetic Field
Replies
5
Views
2K
I Resulting magnetic field due to the passage of an AC current
Replies
27
Views
2K
I Confused about electromotive forces
Replies
10
Views
2K
I Applying Lorentz Force correctly
Replies
1
Views
337
I Can Current Density Static Create an Effective Electromagnetic Shield?
Replies
3
Views
1K
I Hall effect -- is it always applicable?
Replies
7
Views
2K
A Why is "method of image current" valid in magnetostatics?
Replies
4
Views
2K
Why Doesn't Electric Force Cause Wires to Move?
Replies
15
Views
2K

Hot Threads

Recent Insights

Back
Top