To analyze the phenomenon of magnetic induction in more detail, Faraday used a concept that he had created: the lines of force , which we know today as field lines .
In this way, we can say that the number of lines that cross a flat surface, of area A, placed perpendicularly to a magnetic field, is proportional to the product of the magnetic field and the surface area, ( B . A ). This product was called the flux of B (or magnetic flux ) through the surface, represented by ϕ. So we have:
ϕ – magnetic flux
B – magnetic field
A – flat surface area
According to the figure below, we have a loop of area A immersed in a uniform magnetic field. The angle formed between the field B and the vector n normal to the plane of the loop is θ. Thus, to calculate the magnetic flux B through the loop we have to take the angle into account. So we have to:
In the SI (International System of Units) the flow unit is called weber (Wb).