Question

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

Answer 1

$v=E+ir$

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

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