Ampere

Definition

An ampere (A) is the unit of electric current in the International System of Units (SI). It is defined as the flow of one coulomb of charge per second.

5 Must Know Facts For Your Next Test

1. One ampere is equivalent to one coulomb of charge passing through a point in a circuit per second.
2. The ampere is one of the seven base units in the SI system.
3. According to Ampère's force law, two parallel conductors carrying an electric current will exert a force on each other; this force is used to define the ampere.
4. The official definition of the ampere was revised in 2019 based on fundamental physical constants, specifically the elementary charge ($e$).
5. In practical applications, measuring instruments like ammeters are used to measure current in amperes.

Review Questions

• What does one ampere represent in terms of charge and time?
• How do two parallel currents interact according to Ampère's force law?
• What fundamental physical constant was used in defining the ampere after its revision in 2019?

Related terms

Coulomb: The SI unit of electric charge, defined as the quantity of electricity transported by one ampere in one second.

Ampère's Force Law: A principle that states that two parallel conductors carrying electric currents will exert a force on each other proportional to their lengths and currents.

Amperemeter (Ammeter): An instrument used to measure electric current in amperes.