In figure $($a$),$ a $49$ resistor is connected to a battery. Figure $(b)$ shows the increase of thermal energy $E_{th}$ in the resistor as a function of time $t.$ The vertical scale is set by $E_{th}=2\mathrm{.}50mJ,$ and the horizontal scale is set by $t_s=4\mathrm{.}0s.$ What is the electric potential across the battery?

$mV$

How is power related to energy? How is power related to the graph and how is it related to potential difference and resistance?