GCE (A-level) Physics E18 Internal Resistance 4 of 4

How to measure internal resistance (and emf).; Gives a quick method and a longer graphical method. Includes fully worked calculations

[StevePhysics]

The graph could have voltage on the y-axis. Then emf would be the y-axis intercept, as you say.

But we are looking at the ‘characteristic curve’ for a cell. It is conventional to put voltage on the x-axis because voltage is considered to be the independent variable (the one we control during measurements). Current is the dependent variable and therefore goes on the y-axis. This is the ‘standard’ way to draw a characteristic curve. It means emf is the x-axis intercept. But it's not essential.

[sedani]

i think you drew the graph the wrong way round at 5:27, isnt volts meant to be on the y axis because V= emf- Ir, where emf is the y intercept.