Ampere's law
From Conservapedia
Ampere's Law, named for Andre-Marie Ampere, relates electric current to magnetic fields, and is one of Maxwell's Equations. It is often used in the calculation of the magnetic field at a point due to one or many current-carrying wires. It is the magnetic analogue to Gauss's Law, and can be stated in integral form as
where 
is magnetic field, C is a closed curve, 
is current enclosed by C, and 
is the permeability of free space.
In differential form, Ampere's Law is written
where 
is current density.
