Magnetic force of two parallel wires is inverse proportional to distance?

[ctech4285]

according too: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html#c1F=(u * I *I2)/(2pi *r )
i thought it would be inverse proportional to the square of the distance?! can this be right?

 

[Antiphon]

Its right.

The inverse X laws are different in different dimensions. Two infinite parallel wires is a lot like a 2-D problem where its usually the "inverse-r" law.

 

[ctech4285]

ah that makes sense, thanks! 1d -> r; 2d -> 1/r; 3d -> 1/r`2

 

[Antiphon]

To complete your 3D understanding of this, imagine two wires 1km long separated by 1cm.

For these wires, as they are separated the force will go very nearly as 1/r. When they are about 1km apart it will not be 1/r or 1/r^2 but something in between. When they are a million km apart the force will go very nearly as 1/r^2.

(1D goes as a constant or 1/r^0)