# Coulomb definition

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#### kabtq9s

##### Junior Member
15+ Year Member

I am a little confused by the Princeton Review definition of a Coulomb on page 289 of the Physical Sciences book

It says: Coulomb, The SI unit of electric charge, abbreviation C, the fundamental electric charge ( the charge on a proton or the magnitude of the charge on an electron) is defined to be e=1.6x10^-19. Therefore, one coulomb is equal to the total charge on 6.25x10^18 protons

I don't understand the part in bold, because I thought that Coulombs always refer to charge on electrons. Why are they talking about protons now?

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#### SteveJMarist

##### Full Member
5+ Year Member
I am a little confused by the Princeton Review definition of a Coulomb on page 289 of the Physical Sciences book

It says: Coulomb, The SI unit of electric charge, abbreviation C, the fundamental electric charge ( the charge on a proton or the magnitude of the charge on an electron) is defined to be e=1.6x10^-19. Therefore, one coulomb is equal to the total charge on 6.25x10^18 protons

I don't understand the part in bold, because I thought that Coulombs always refer to charge on electrons. Why are they talking about protons now?

Well, because the charge on electrons is the charge on protons but just negative. So, the total charge on -1 C = charge of 6.25 x 10^18 electrons, 1 C = charge of 6.25 x 10^18 protons.

#### kabtq9s

##### Junior Member
15+ Year Member
Well, because the charge on electrons is the charge on protons but just negative. So, the total charge on -1 C = charge of 6.25 x 10^18 electrons, 1 C = charge of 6.25 x 10^18 protons.

so are you saying that the electrical charge of 6.25 x 10^18 electrons equals 1.6x10^-19, which is the same charge of 6.25 x 10^18 protons.

Ps. your avatar is the most motivating thing I saw today, thanks for making it

#### Catburr

##### Full Member
7+ Year Member
One coulomb is the amount of charge transported by one ampere of current in one second of time. That's just the definition for the magnitude of one coulomb though, once you've agreed on that magnitude, you can apply it to positive or negative charge.

One electron or one proton has the MAGNITUDE of charge: 1.6 x 10^-19 Coulombs.

One coulomb is the MAGNITUDE of the amount of charge on 6.2 x 10^18 protons OR electrons.

#### kabtq9s

##### Junior Member
15+ Year Member
One coulomb is the amount of charge transported by one ampere of current in one second of time. That's just the definition for the magnitude of one coulomb though, once you've agreed on that magnitude, you can apply it to positive or negative charge.

One electron or one proton has the MAGNITUDE of charge: 1.6 x 10^-19 Coulombs.

One coulomb is the MAGNITUDE of the amount of charge on 6.2 x 10^18 protons OR electrons.

Thanks so much Catburr, now I get it.