Find equivalent resistance between $A$ and $B$

A wire has resistance of $24 \mathrm{\Omega }$ is bent in the following shape. The effective resistance between $A$ and $B$ is

The figure below shows currents in a part of electric circuit. The current $i$ is

The figure here shows a portion of a circuit. What are the magnitude and direction of the current $i$ in the lower right hand wire?

A group of $N$ cells whose emf varies directly with the internal resistance as per the equation $E_N=1.5r_N$ are connected, as shown in the figure. The current $I$ in the circuit is

Two batteries of emf ${\epsilon }_1$ and ${\epsilon }_2\left({\epsilon }_2>{\epsilon }_1\right)$ and internal resistances $r_1$ and $r_2$, respectively are connected in parallel, as shown in the figure.

In an experiment, a graph was plotted of the potential difference $V$ between the terminals of a cell against the circuit current $i$ by varying load rheostat. Internal conductance of the cell is given by