The proportionality
constant in SI units has the exact value,
7
0
10
Tm/A
µ4
−
π=
[4 11(c)]
We call m0 the permeability of free space (or vacuum) The Biot-Savart law for the magnetic field has certain similarities, as
well as, differences with the Coulomb’s law for the electrostatic field Some
of these are:
(i)
Both are long range, since both depend inversely on the square of
distance from the source to the point of interest