Coulomb
This article is about the unit. For other meanings, see Coulomb (disambiguation).
The coulomb [kuˈlõː] (unit symbol: C, formerly Cb) is the SI unit of electric charge (formula symbol Q or q). It is named after the French physicist Charles Augustin de Coulomb.
1 coulomb is the electric charge transported within one second through the cross-section of a conductor in which an electric current of the strength of one ampere flows:
The coulomb is therefore also referred to as the ampere-second (As). The ampere-hour (Ah) commonly used to denote battery capacity is accordingly 3600 As = 3600 C.
Definition
The definition of the units coulomb and ampere is based on the elementary charge, which was defined as exactly 
has been established, see International System of Units.
Historical
In 1861, the two English electrical engineers Josiah Latimer Clark and Charles Tilston Bright proposed the farad as the unit for electric charge in honour of the English physicist Michael Faraday. In 1881, however, the International Electricity Congress established the coulomb as the unit for electric charge and the farad as the unit for electric capacitance.
The current definition of the coulomb by defining the elementary charge was adopted at the 26th General Conference on Weights and Measures on November 16, 2018, and became effective May 20, 2019. Previously, the ampere had been defined by the Lorentz force of the electric current, and the coulomb as an ampere-second.
Questions and Answers
Q: What is a coulomb?
A: A coulomb is a unit of electric charge.
Q: Who is Charles-Augustin de Coulomb?
A: Charles-Augustin de Coulomb was a scientist who studied electric charge in the late 1700s. The coulomb is named after him.
Q: What is current in an electric circuit?
A: Current in an electric circuit is the movement of electric charge.
Q: If a flashlight bulb has a current of one ampere, how many coulombs of charge will pass through it every second?
A: If a flashlight bulb has a current of one ampere, one coulomb of charge will pass through it every second.
Q: What particle carries the charge that moves in an electric wire?
A: The particle that carries the charge that moves in an electric wire is the electron.
Q: What is the smallest electric charge found in a stable particle?
A: The smallest electric charge found in a stable particle is the elementary charge.
Q: How many elementary charges are there in a coulomb?
A: There are 6,241,509,629,152,650,000 elementary charges in a coulomb.
