Magnetic flux area S is where "B" is the magnitude of the magnetic field (the magnetic flux density) having the unit of Wb/m (tesla), "S" is the area of the surface, and "θ" is the angle between the magnetic field lines and the normal (perpendicular) to S. For a varying magnetic field, we first consider the magnetic flux through an infinitesimal area element dS, where we may consider the field to be constant: A generic surface, S, can then be broken into infinitesimal elements and the total magnetic flux through the surface is then the surface integral From the definition of the
Flux quantum state ψ(r, t) have a probability density defined as So the probability of finding a particle in a differential volume element dr is Then the number of particles passing perpendicularly through unit area of a cross-section per unit time is the probability flux; This is sometimes referred to as the probability current or current density, or probability flux density. As a mathematical concept, flux is represented by the surface integral of a vector field, where F is a vector field, and d"A" is the vector area of the surface "A", directed as the surface normal.For the second,n is the