When an external resistance of \( 5 \, \Omega \) is connected across terminals of a cell, a current of \( 0.25 \, \text{A} \) flows through it. When the \( 5 \, \Omega \) resistor is replaced by a \( 2 \, \Omega \) resistor, a current of \( 0.5 \, \text{A} \) flows through it. The internal resistance of the cell is ___________ \( \Omega \).