Why is a definition of a coulomb the energy transferred from one amp over one second, but then the definition of an amp is one coulomb moving past a point in one second? The definitions use eachother! So how can you define this with something else that already uses the word!?

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Answer 1

Those are not the definition

That coulomb definition could not work, coulomb is a unit of electric charge not a unit of energy.

The ampere definition is functionally the same as the definition used today but with the correct coulomb definition, it works fine.

SI base units changed the definition in 2019

A ampere is SI base unit the pre 2019 definition was

>The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 m apart in vacuum, would produce between these conductors a force equal to 2×10−7 newton per metre of length.

The 2019 definition is

>The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602176634×10−19 when expressed in unit C, which is equal to A⋅s, where the second is defined in terms of ΔνCs.

​

From it follow that a coulomb is

1 C = e/ (1.602176634×10^−19)

Where e is the elemental charge.

We can take 1/ (1.602176634×10^−19) and calculate and round it to an integer and we get 6 241 509 074 460 762 608

So a coulomb is the change of a bit over six quintillion electron charges.

So a coulomb is defined as a specific number of electrons and ampere is the current of 1 coulomb per second