Gauss's Law for Magnetism
Maxwell's second equation stating that the total magnetic flux passing through any closed surface is always identically zero.
Governing formula
Φ_B = ∮ B · dA = 0, ∇ · B = 0
SI unit
Wb (Webers)
In depth
This law dictates that isolated magnetic monopoles do not exist in nature. Every magnetic source possesses paired North and South poles, so magnetic field lines always form continuous, closed vector loops.
Examples in the real world
Cutting a bar magnet in half produces two smaller, complete bar magnets, each possessing its own distinct North and South poles.