Magnetic field

Magnetic flux

The mathematical concept of magnetic flux is helpful when you deal with induced currents. It is time, therefore, to include its definition here.

The magnetic flux through a surface is equal to the following scalar product:

where B is the magnetic induction and ΔS is the surface vector. In the above visual, you can study the variation of flux with each of the variables involved.

When the field is not homogeneous, or the surface is curved, it is necessary to imagine the suface divided into small elements dS and sum (integrate) the flux through each of these elements. Here is a general expression for the value of the flux through an arbitrary surface:

	Natural magnets
	Lines of force
	Magnets and currents
	Conclusions

	on a charged particle
	on a straight cable
	on a loop
	Conclusions

	by a charged particle
	by a rectilinear current
	by a coil
	An explanation of natural magnetism
	Conclusions

	Magnetic flux
	The laws of Faraday and Lenz
	Self-induction
	Conclusions

	The generation of alternating currents
	A circuit of alternating current
	Conclusions