Two coils with self-inductance $1 H$ and $3 H$ are connected in series. Their mutual inductance is $5 H$. The equivalent self-inductance of the combination is: (in $H$)

Two inductors of $80 \ mH$ each are joined in parallel. The current passing through the combination is $2.1 \ A$. The energy stored in this combination of inductors is

Two coils of self-inductances $6 mH$ and $8 mH$ are connected in series and are adjusted for the highest coefficient of coupling. The equivalent self-inductance $L$ for the assembly is approximately: (in $mH$)

Two inductors,each of inductance $L$,are connected in parallel. One more inductor of value $5 \text{ mH}$ is connected in series with this configuration,and the effective inductance is $15 \text{ mH}$. The value of $L$ is . . . . . . $\text{mH}$.

Two pure inductors each of self inductance $L$ are connected in parallel but are well separated from each other. The total inductance is

The equivalent inductance between $A$ and $B$ is ..... $H$.