A battery drives a larger current when its external resistance is reduced. What happens to the potential difference across its terminals?

1. The emf depends only on the chemical reaction inside the battery, so it does not change. 2. The potential difference lost inside the battery is the current multiplied by the internal resistance. 3. A larger current therefore means a larger loss inside the battery. 4. Since the emf is fixed, what is left at the terminals must be smaller. 5. The terminal potential difference equals the emf only when the current is very small, so it cannot stay the same. _Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 10: Electric circuits_