Alead acid battery with 12 cells connected in series (no-load voltage=2.1 volts per cell) furnishes 10 amperes to a load of 2-ohms resistance. the internal resistance of the battery in this instance is?

Explanation:

As we know that total potential of all cells when they are in series is given as

so we have

now total resistance of all 12 cells which are in series is given as

external resistance is given as

now by Ohm's law we know that

so we have

see earlier answer