Electromagnetic

Electromagnetic fields

There are 6 mathematical quantities which are used to describe electromagnetic fields in 3 distinct cases. The electric field, E, and magnetic flux density, B are used to describe the electromagnetic fields in cases where all the charges are known directly such as the electromagnetic field in a vacuum. To describe the case where the charges inside of a material respond to applied electric and magnetic fields, it is useful to define the electric displacement field, D and magnetic field strength, H, in addition to E and B. Finally, it is sometimes useful to describe electromagnetic fields not in terms of force but in terms of potential energy and momentum. In this case, the electromagnetic field is represented by the electric potential, V, and the magnetic vector potential, A, respectively.