Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: The internal resistance r can behave in complex ways. As noted, r increases as a battery is depleted. But internal resistance may also depend on the magnitude and direction of the current through a voltage source, its temperature, and even its history. The internal resistance of rechargeable nickel-cadmium cells, for example, depends on how many times and how deeply they have been depleted. Answer: increases
A:
As a battery is depleted what happens to its internal resistance?