Ampere-Hour (Ah) measures what aspect of a battery?

• A. Discharge rate
• B. Voltage
• C. Charge capacity of a battery, or how much current can be delivered at a constant rate as the battery is depleted over the course of one hour.
• D. Physical size

Answer: (C)

Ampere-hours quantify how much electrical charge a battery can store and therefore how much current it can deliver over time. It’s the product of current and time, so delivering 1 amp for 1 hour equals 1 Ah, while delivering 2 amps for half an hour also equals 1 Ah. This rating reflects the battery’s charge capacity, not its voltage or physical size. The total stored energy depends on both this capacity and the voltage, since energy equals voltage times Ah. So the idea being tested is that Ah measures the battery’s charge capacity—the amount of current it can deliver at a constant rate over a standard one-hour period.