Electromagnetic theory covers the basic principles of electromagnetism: experimental basis, electrostatic, magnetic fields of stable currents, e.m.f motional. And electromagnetic induction, Maxwell's equations, the propagation and radiation of electromagnetic waves, the electrical and magnetic properties of matter, and the laws of conservation. This is a postgraduate level subject who uses appropriate mathematics, but whose emphasis is on physical phenomena and principles.
The history of electromagnetic theory begins with ancient measures to understand atmospheric electricity, particularly lightning. People then had little understanding of electricity, and were unable to explain the phenomena. The scientific understanding of the nature of electricity grew throughout the eighteenth and nineteenth centuries through the work of researchers such as Ampère, Coulomb, Faraday and Maxwell.
In the nineteenth century it had become clear that electricity and magnetism were related, and their theories were unified: wherever the charges are in motion, the electric current results and the magnetism is due to the electric current. The source for the electric field is the electric charge, while for the magnetic field is the electric current (moving charges).