An (EMF) ElectroMagnetic Field is a physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction. It is one of the four fundamental forces of nature (the others are gravity, strong nuclear force, and weak nuclear force).
The strength of an electromagnetic field is measured by its electric field E and magnetic field B. Both fields are vector fields; their strengths are expressed as vectors with magnitude and direction. The directions of E and B at any given point in space can be determined using the right-hand rule: if you curl your fingers in the direction that a positive charge would move them under the influence of E, then your thumb points in the direction of B (at that point).
The strength of an electromagnetic field is measured in units called volts per meter (V/m). The SI Unit for measuring electric fields is volt per meter (V/m), while that for magnetic fields is ampere per meter (A/m). Electric fields are created by stationary charges, while magnetic fields are created by moving charges (currents); thus, they are sometimes referred to as electrostatic and magnetostatic fields, respectively. In general relativity theory combined electromagnetism and gravity into a single theory—the geometrical Einstein–Hilbert action—which explains both phenomena within a unified framework.
In classical physics, electricity and magnetism were considered to be two separate forces; however beginning with James Clerk Maxwell’s 1873 publication A Treatise on Electricity and Magnetism these ideas were unified into Maxwell’s equations which describe both electricity and magnetism as aspects manifestations of a single underlying electrodynamic force governed by four partial differential equations: Gauss’s law for electricity; Gauss’s law for magnetism; Faraday’s law of induction; Ampère–Maxwell law.