Magnetic flux

Magnetic flux, or simply flux, is the physical quantity that specifies the amount of a magnetic field, its symbol being Φ or φ and its unit, the weber (Wb). The flux per unit area is referred to as (magnetic) flux density, and its symbol is B. The unit of flux density is T in the SI system, but gauss (G) in the cgs system. In motors or transformers, the flux linkage or the flux linked with the number of turns is a more important quantity and is specified by ψ or Ψ We may say that the magnetic flux multiplied by the number of turns is the flux linkage. The unit of flux linkage is Wb, too.
The strength and direction of a magnetic field, 1 Weber (Wb), is represented by a bundle of lines.