Magnetic Flux Density(B):

k.I/D

where

I=Current in amperes

D=Distance from Conductor

k=constant 

Absolute permeability of the magnetic material. 

S=L/ μ A

S is the reluctance of the magnetic path, L is the length of the path (in meters), A is the cross-sectional area of the path (in square meters), and μ is the absolute permeability of the magnetic material.

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