# What is total magnetic flux through a coil?

According to Gauss's law of magnetism, the total magnetic flux through a closed surface is zero. But during induction, we study that the magnetic field lines passing through a coil change, as does flux given by $\Phi = LI$. But even if they change, the net lines coming in= net lines going out. So, flux should be zero?

• What do mean with: "net lines coming in= net lines going out"? Jun 9, 2017 at 11:03
• I mean that the total number of magnetic field lines are equal to the total number of magnetic field lines going out Jun 9, 2017 at 11:05
• For coil magnetic flux, the surface the magnetic field lines pierce is not closed. Jun 9, 2017 at 12:07

But as you stated magnetic flux through a coil is given by $$\Phi = LI$$
So flux is not zero for $I, L \ne 0$.
According to Gauss' Law, the "net" magnetic flux is zero for a closed surface because magnetic monopoles don't exist but by writing $$\Phi=LI$$, we measure the outflux/influx produced by the single pole but though the "net" flux here also is zero.