What is the elementary charge?
The elementary charge is e = 1.602176634e-19 C, exact by SI definition (zero uncertainty). It is the electric charge of a proton (and minus that of an electron).
Open the interactive PhysRef tool →Key facts
| Value | 1.602176634e-19 C |
|---|---|
| Symbol | e |
| Exactness | Exact by SI definition (uncertainty 0) |
| Meaning | Charge of one proton |
| Source | CODATA 2018 |
Frequently asked questions
What is the value of the elementary charge?
e = 1.602176634e-19 coulombs, an exact defining constant of the SI since 2019.
Is the elementary charge exact?
Yes, since 2019 it is fixed exactly and is used to define the ampere.
How does e relate to the electronvolt?
1 eV = 1.602176634e-19 J, numerically equal to e in coulombs, because 1 eV is e times 1 volt.
Related pages
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