Magnetic moment and external fields is not part of this internal energy. The unit for magnetic moment in terms of the International System of Units (SI) base units is A⋅m, where A is the ampere (the SI unit of current) and m is the meter (the SI unit of distance). This has equivalents in other units used in SI including: where N is the newton (the SI unit of force), T is the tesla (the SI unit of magnetic flux density), and J is the joule (the SI unit of energy). In the CGS system, there are several different sets of electromagnetism
Magnetic circuit is given by the product of the magnetic field and the area element. More generally, magnetic flux Φ is defined by a scalar product of the magnetic field and the area element vector. Quantitatively, the magnetic flux through a surface "S" is defined as the integral of the magnetic field over the area of the surface For a magnetic component the area S used to calculate the magnetic flux Φ is usually chosen to be the cross-sectional area of the component. The SI unit of magnetic flux is the weber (in derived units: volt-seconds), and the unit of magnetic field