How do I work out what has the smallest EMF?

I’m also confused at what voltage over amp even shows? meh

If you are asking about the smallest potential difference,then I’d explain you the process.

Let’s take the instance of cell A.It started at pd. 1.6V at 0 Ampere and at 2 amperes it ended at 1.4 volts.
So the total p.d is 1.6 – 1.4 = 0.2 volts

B Started at 1.4 volts and ended at 0 volts so the drop in potential is 1.4 volts.

C started with 1.o volt and ended at 0.2 volt so the total drop is 0.8 volts.

So the smallest drop for the same amount of current drawn is 0.2 volts which is in case of A.

If you still need any help please ask.I’ve to run for the soccer practice,but once I’m back or next time I log in,I’ll clarify your doubts.

@engineeristerminatorisWOLV
Thanks, this is what I thought.

@Timebomb :You’re Welcome.