Question

The potential difference between the terminals of a $6.0V$ battery is $7.2V$ when it is being charged by a current of $2.0A$. What is the internal resistance of the battery?

Answer 1

$V=\in +ir$

$\Rightarrow 7.2=6+2\times r$

$\Rightarrow 1.2=2r\Rightarrow r=0.6\Omega$