A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire,…

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $\displaystyle 2.0$ V and a negligible internal resistance. The potentiometer wire itself is $\displaystyle 4$ m long. When the resistance, R, connected across the given cell, has values of.

infinity

$\displaystyle 9.5 \Omega$,

the 'balancing lengths', on the potentiometer wire are found to be $\displaystyle 3$ m and $\displaystyle 2.85$ m, respectively.

The value of internal resistance of the cell is :