Final answer:
To calculate the internal resistance of the battery, use the formula V = EMF - Ir. The correct calculation for the given question points to an internal resistance of approximately 0.11 ohms, which is not listed in the provided options.
Step-by-step explanation:
To find the internal resistance of a battery, we can use the formula V = EMF - Ir, where V is the terminal voltage, EMF is the electromotive force of the battery, I is the current, and r is the internal resistance. In this case, we have a battery with a 12.2 V EMF, a terminal voltage of 10.2 V, and it is delivering 18.9 A to a car starter. Therefore, we can rearrange the formula to solve for r:
r = (EMF - V) / I
Substituting the given values:
r = (12.2 V - 10.2 V) / 18.9 A
r = 2 V / 18.9 A
r = 0.10582 ohms, which rounds to 0.11 ohms to two decimal places. None of the provided options (a) 0.74 ohms, (b) 1.20 ohms, (c) 0.53 ohms, or (d) 0.96 ohms exactly match this calculated value. Therefore, it might be a trick question or there might be a typo in the options provided. However, the correct calculation based on the given information points to an internal resistance of approximately 0.11 ohms.