We call these four field equations Maxwell’s Equations, and they will be the primary focus of this course. Maxwell’s equations in combi-nation with Lorentz’s Force Law tell us that charges can forces on other charges at a distance. Much of electrical engineering involves using these forces to do something useful. For example, when I re-ceive signals in a radio I am really detecting the forces exerted on the electrons in my antenna by the moving electrons in the transmitting antenna. When I see starlight, I am detecting the forces generated on the electrons in my eyes by the moving charged particles in the star.
The four field equations as written on the previous page are valid in free space, including the empty space between sub-atomic particles. However, we shall learn that when we deal with matter on a macro-scopic scale, it will be useful to work with modified forms of these equations.
