You have emphasized visualization. Maxwell's equations which describe electricity and magnetism, lend themselves quite well to this purpose. I will give a brief statement of what each relevant equation says as well as the equation and a visual interpretation of the equation. read more
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). read more