The logic of the self inductance formula

[nabliat]

M_{12}=\frac{N_2\phi _{12}}{I_1}

i need to remmeber it

but i can't see the logic of
the formula
??

 

[roam]

M_{12}=\frac{N_2\phi _{12}}{I_1}

i need to remmeber it

but i can't see the logic of
the formula
??

I thought the formula looked something like: \frac{\mu_{0}N^2 A}{l}. A is the cross section & magnetic field inside the solenoid is B=\mu_0 NI/l, flux through one loop is BA=\mu_0 N IA/l and \Phi= \mu_0 N^2 I A/l is the total flux. The inductance is just total flux divided by current.