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

Answer:

$r = 0.043 ohm$

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

$25.2 = 10 (2 + 12 r)$

$r = 0.043 ohm$