Question

What is the internal resistance of a 12.0 V car battery whose terminal voltage drops to 8.2 V when the starter draws 75 A

Answer 1

Answer:

The internal resistance of the cell is 0.051 ohm.

Explanation:

Given;

emf of the battery, E = 12 V

terminal voltage of the cell, V = 8.2 V

current in the circuit, I = 75 A

let the potential drop of the cell due to internal resistance (r) = Ir

The internal resistance of the cell is calculated from the equation below;

E = V + Ir

where;

r is the internal resistance of the cell

$Ir = E - V\\\\r = \frac{E-V}{I} \\\\r = \frac{12-8.2}{75} \\\\r = 0.051 \ ohm$

Therefore, the internal resistance of the cell is 0.051 ohm.