magnetic monopoles were discovered, then Gauss's law for magnetism would state the divergence of B would be proportional to the magnetic charge density ρm, analogous to Gauss's law for electric field. For zero net magnetic charge density (ρm = 0), the original form of Gauss's magnetism law is the result.
The modified formula in SI units is not standard; in one variation, magnetic charge has units of webers, in another it has units of ampere-meters.
Units
Equation
cgs units[7]
ablacdotmathbf{B} = 4pi
ho_m
SI units (weber convention)[8]
ablacdotmathbf{B} =
ho_m
SI units (ampere-meter convention)[9]
ablacdotmathbf{B} = mu_0
ho_m