magnetic flux density A vector quantity measuring the strength and direction of the magnetic field around a magnet or an electric current. Magnetic flux density is equal to magnetic field strength times the magnetic permeability in the region in which the field exists. Electric charges moving through a magnetic field are subject to a force described by the equation F = qv × B, where q is the amount of electric charge, v is the velocity of the charge, B is the magnetic flux density at the position of the charge, and × is the vector product. Magnetic flux density also can be understood as the density of magnetic lines of force, or magnetic flux lines, passing through a specific area. It is measured in units of tesla. Also called magnetic flux, magnetic induction. 
magnetic induction
