Two coils of self inductances, L1 and L2 are placed so close together that effictive flux in one coil completely linked with the other. If M is the mutual inductances between them then
M =L1 L2
`M = (L_1 L _2)^2`
`M =L1//L2`
`M =sqrt(L_1 L_2)`
How is the mutual inductance between the two coils root of L1L2