In the arrangement of resistances shown below,the effective resistance between points $A$ and $B$ is ............... $\Omega$.

$A$ heating coil can heat the water of a vessel from $20\,^oC$ to $60\,^oC$ in $30$ minutes. Two such heating coils are put in series and then used to heat the same amount of water through the same temperature range. The time taken now will be ............ $min$ (neglecting thermal capacity of the coils).

Calculate the equivalent resistance across $A-B$ in the given circuit. ............... $\Omega$

The equivalent resistance between points $A$ and $B$ in the given network is: (in $\Omega$)

The effective resistance of the network between points $A$ and $B$ is

In this circuit,the value of $I_2$ is (in $A$)