Nine resistors each of resistance $R$ are connected in the circuit as shown in the figure. The net resistance between $A$ and $B$ is,

For the network of resistance shown in the figure the equivalent resistance of the network between the points $A$ and $B$ is $18$ ohm. The value of unknown resistance $R$ is:-

For what value of the resistor $X$ will the equivalent resistance of the two circuits shown be the same?

Two batteries $V_1$, and $V_2$ are connected to three resistors as shown below.

If $V_1=2 \mathrm{V}$ and $V_2=0 \mathrm{V}$, the current $I=3 \mathrm{mA}$. If $V_1=0 \mathrm{V}$ and $V_2=4 \mathrm{V},$ the current $I=4 \mathrm{mA}$. Now if $V_1=10 \mathrm{V}$ and $V_2=10 \mathrm{V},$ the current $I$ will be