e
elementary charge
Electric chargeexact by definition
The elementary charge is the magnitude of the charge on a single proton, and the negative of the charge on an electron. Since 20 May 2019 it has had the exact defined value of 1.602176634e-19 coulombs, which is what now fixes the size of the ampere. Before that date it was a measured constant with an uncertainty in its final digits.
Watch out: Quarks carry charges of one third and two thirds of the elementary charge, but they are never observed in isolation, so every free particle has a charge that is a whole multiple of e.
| 1 e | 1.6021766e-19 C |
Solvers that use electric charge