Why magnetic field from a current carrying conductor obey inverse-square law?

AI Thread Summary
The discussion centers on the behavior of magnetic fields produced by current-carrying conductors, specifically questioning why they would follow an inverse-square law like electric fields from point charges. It is noted that the static magnetic field does not decrease as 1/R^2; instead, it diminishes as 1/R for an infinite linear conductor. The conversation also touches on the necessity of a closed circuit for a static magnetic field to exist and distinguishes between static and dynamic (AC) fields. Additionally, there is confusion regarding the application of geometric explanations for magnetic field behavior, with participants clarifying that the magnetic field's fall-off is not analogous to that of electric fields. Ultimately, the consensus is that the magnetic field does not follow an inverse-square law in the context discussed.
NANDHU001
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I have read that the electric field from a point charge fall off as 1/(r*r) since it is analogous to
variation of intensity of radation from source (whose geometric proof depends on solid-angle), similarily is there any geometric explanation why magnetic field in the stated case fall off as 1/(r*r).
 
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Bizarre "proof" that the static electric field is analoguous to a radiation... What about the gluon force? It increases over distance. What tells the previous reason in this case?

As for the static magnetic field... It cannot decrease as 1/R^2 because this would need a permanent current in an open wire. Either it's static, and then you need to close the circuit, and this loop creates a field as 1/R^3, or you have an antenna which accepts only AC current, and radiates an electromagnetic field, not a static magnetic one.

So 1/R^2 exists only as a computation intermediate of static magnetic fields.
 
NANDHU001 said:
similarily is there any geometric explanation why magnetic field in the stated case fall off as 1/(r*r).

It doesn't, does it?
The magnetic field of an infinite, linear conductor goes like 1/r where r is the distance from the wire (along the radius of a cylinder coaxial with the wire).
Maybe you mean a different geometry of the current carrying conductor?
 
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