Charge from Current

Electric current is the rate at which electric charge flows past a point, so if the current stays constant, the total charge transferred is just rate × time. That is why multiplying current by time gives charge: a larger current moves more charge each second, and a longer time allows that flow to continue for more seconds. The unit check also works out, since 1 ampere equals 1 coulomb per second, so A × s becomes coulombs.

Use this formula when a circuit has a steady current and you need to find how much charge passes through a wire, component, or battery over a given time. It is common in basic circuit problems, electrolysis, and any situation involving constant current flow.

• Using time in minutes or hours without converting to seconds first
• Mixing up current and charge by putting amperes as the answer instead of coulombs
• Using this formula when the current is changing instead of constant