Three coils of self inductance, 5, 10 and 15 Mh are connected first in series an then in parallel. What is the ration of the net inductance in the two cases?

Two pure inductors each of self inductance L are connected in series,the net inductance is

Two pure inductors each of self inductance L are connected in series, the net inductance is

Two coils of self inductance 1 H and 3H are connected in series to support each other. Their mutual inductance is 6H. What is the self inductance of the combination ?

Two inductor coils with inductances 10 mH and 20 mH are connected in series .What is the resultant inductance of the combination of the two coils?

Two coils of self-inductances 6mH and 8mH are connected in series and are adjusted for highest coefficient of coupling. Equivalent self-inductance L for the assembly is approximately