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

[cataldo]

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 ?

 

[Meir Achuz]

For the same current, the magnetic field at the surface is proportional to 1/R.

 

[cataldo]

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

 

[Bob S]

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.