# Magnetic flux

1. Oct 19, 2009

### phymatter

Is it possible to have magnetic flux through an open surface ?
i mean if there is a circular arc and magnetic field at the centre changes with time then will there be any induced emf in the arc ?????????

2. Oct 19, 2009

### rplatter

Yes it is possible.

Magnetic fields travel through space.
They like to travel through some materials better than others(Ferric), so you can guide them with the right material.

Definition/Summary
Flux sometimes means total flow through a surface (a scalar), and sometimes means flow per unit area (a vector).

In electromagnetism, flux always means total flow through a surface (a scalar).

Scalar flux is the amount of a vector field going through a surface: it is the integral (over the surface) of the normal component of the field:

For a closed surface, this equals (Gauss' theorem, or the divergence theorem) the integral (over the interior) of the divergence of the field: .

Therefore the scalar flux, through a closed surface, of an electric field is proportional to the enclosed charge (Gauss' law: ), and of a magnetic field is zero (Gauss' law for magnetism: ).