Ampereseconds

Ampereseconds, written as A·s, is the SI unit used to quantify electric charge. It represents the amount of charge that passes a point in a circuit when a current of one ampere flows for one second. By definition, 1 A·s equals 1 coulomb (C), the standard SI unit of electric charge.

In terms of equations, the charge Q that passes through a conductor is the time integral of current: Q = ∫ I dt. If the current is constant, this simplifies to Q = I t. For example, a current of 2 A flowing for 3 seconds transfers 6 A·s (6 C) of charge.

Although the coulomb is the official unit for electric charge, ampereseconds are sometimes used in more descriptive contexts to refer to the amount of charge moved over a time interval. In practice, engineers and physicists typically prefer coulombs for charge, while ampere-hours (Ah) are used to express battery capacity, with the relation 1 Ah = 3600 C = 3600 A·s.

Overall, ampereseconds are a direct way to express charge resulting from current over time, and they are numerically equivalent to coulombs, though coulombs remain the standard unit in formal SI usage.