Question

A lead 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?

Answer 1

`r = 0.043 ohm`

Step-by-step explanation:

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

`V = V_1 + V_2 + V_3 + ....................`

so we have

`V_(net) = 12(2.1) = 25.2 Volts`

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

`r_(net) = 12 r`

external resistance is given as

`R = 2 ohm`

now by Ohm's law we know that

`V_(net) = i (R + r_(net))`

so we have

`25.2 = 10 (2 + 12 r)`

`r = 0.043 ohm`