Magnetic flux $$\mathit{\Phi}$$ through a cross-sectional area $$A$$ is defined as the scalar product between the magnetic flux density $$\class{violet}{\boldsymbol{B}}$$ and the surface normal vector $$\boldsymbol{A}$$. The surface normal vector $$\boldsymbol{A}$$ and $$\class{violet}{\boldsymbol{B}}$$ field vector enclose an angle $$\varphi$$.