When an external resistance of 5 Ω is connected across terminals of a cell, a current of 0.25 A flows through it. When the 5 Ω resistor is replaced…

When an external resistance of $\displaystyle 5 \Omega$ is connected across terminals of a cell, a current of $\displaystyle 0.25$ A flows through it. When the $\displaystyle 5 \Omega$ resistor is replaced by a $\displaystyle 2 \Omega$ resistor, a current of $\displaystyle 0.5$ A flows through it. The internal resistance of the cell is $\displaystyle \_\_\_\_$ $\displaystyle \Omega$.