# Why is a Coulomb not a fundamental unit? [duplicate]

Why is a coulomb not a fundamental unit but an ampere is considering that a coulomb is more ' fundamental '?

## marked as duplicate by sammy gerbil, David Hammen, M. Enns, Jon Custer, YashasJul 29 '17 at 17:44

A fundamental unit is defined as

one of a set of unrelated units of measurement, which are arbitrarily defined and from which other units are derived.

As per wikipedia:

The SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere".

The coulomb is defined using the ampere, so per the definition, it's not fundamental. The ampere is, because it isn't defined using other units.

• It's defined so because it's defined so... -1 – OON Jul 29 '17 at 15:21
• @OON it's not fundamental because it doesn't fit the definition. What more do you want? – heather Jul 29 '17 at 15:29
• Because (as was already noted in the answers to other similar questions) there is a reason to choose specific units as base ones and other as derived. This reason is the difference in practicality and precision of the experiments that are used to define base units or derived ones. – OON Jul 29 '17 at 16:28