A battery having a fixed internal resistance is connected to a resistor with resistance $250\,\Omega$, as shown. For a period of $60\,\text{s}$, the current in the resistor is $40\,\text{mA}$. Over this interval, $6.0\,\text{J}$ of energy is dissipated by the internal resistance. How much energy is delivered to the external resistor during the $60\,\text{s}$, and what is the electromotive force (e.m.f.) of the battery?
Physics 9702 · AS & A Level · Practical circuits