The pure inductors,each of inductance $6 \ H$,are connected as shown in the figure. Their equivalent inductance between the points $P$ and $Q$ is (in $H$)

Initially,the switch $S$ is open and the energy stored in the inductance $L$ connected in series with the battery is $E$. Now,the switch $S$ is closed. The energy stored in both the inductors after a long time is

Two coils of self-inductance $L_{1}$ and $L_{2}$ are connected in series. If the mutual inductance of the coils is $M$,the equivalent self-inductance of the combination shown in the figure will be:

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

An inductor coil of inductance $L$ is divided into two parts and both parts are connected in parallel. The net inductance is

In the given circuit below,the inductance values of $L_1$,$L_2$,and $L_3$ are the same. The magnetic energy stored in the entire circuit is $U_t$ and that stored in the $L_2$ inductor is $U_l$. The ratio $U_t/U_l$ is . . . . . . . (Ignore the mutual inductance,if any.)