Analysis Once your data has been collected, use EXCEL to graph V vs I.
Theoretically, the voltage lost across each combination of resistors represents the terminal voltage of the battery. This voltage can also be calculated with the equation V = ε - Ir where r is the internal resistance of your battery.
Rearranging the equation for terminal voltage, V = ε - Ir, leads to the expression V = -Ir + ε Consequently, your graph of voltage vs current should have a negative slope whose numerical value represents the internal resistance of the battery while the line's y-axis intercept represents the emf of the battery. |