Does a Conductor's Diameter Affect Its Magnetic Field Strength?

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Discussion Overview

The discussion centers on the relationship between the diameter of conductors and the strength of the magnetic field they produce when carrying the same current. Participants explore theoretical implications and practical observations related to magnetic fields generated by conductors of different diameters.

Discussion Character

  • Technical explanation, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant suggests that the maximum magnetic field occurs on the surface of the 20mm diameter conductor, questioning whether this is correct.
  • Another participant states that for the same current, the magnetic field at the surface is inversely proportional to the radius of the conductor.
  • A participant expresses uncertainty, recalling a discussion where a friend claimed the magnetic field was higher on the 50mm diameter conductor.
  • One participant provides equations for the magnetic field both inside and outside an infinite straight conductor, indicating that the field strength scales differently based on the radius and distance from the center.
  • The impact of AC current and eddy currents on the distribution of current within the conductor is mentioned, suggesting that this may influence the magnetic field strength.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are competing views regarding which conductor produces a stronger magnetic field at the surface. The discussion remains unresolved with differing opinions on the effects of diameter on magnetic field strength.

Contextual Notes

The discussion includes assumptions about the nature of the conductors and the type of current (DC vs AC) without fully resolving how these factors influence the magnetic field strength.

cataldo
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I have two conductors in no magnetic material such as copper. One has diameter 20mm and other has diameter 50mm and both through by same current about 100A. Where do i have the maxi magnetic field on surface of conductor...I tinks on conductor with diameter 20mm..Is exactly ?
 
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For the same current, the magnetic field at the surface is proportional to 1/R.
 
Tanks cleam.. Excuse me for the stupid question but i had one discussion with my friend which sayed that the magnetic field at the surface was higher on conductor with diemater 50mm ...
Bye
 
If the two conductors are isolated from one another, the higher field is at the surface of the 20 mm conductor. The B field outside an infinite straight conductor of radius R is

B = 2 x 10-7 I/a tesla (a>R)

where a is the distance from the center of the conductor. The field inside the wire is

B = 2 x 10-7 r I/R2 tesla

where r is a point inside a conductor of radius R (r<=R)

So the field scales as r inside the conductor, and 1/a outside. If the current is an AC current, Eddy currents force the currents toward the surface of the conductor.
 

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