The charge of a subatomic particle is typically measured relative to the elementary charge, denoted as "e." The elementary charge is the fundamental unit of electric charge in the International System of Units (SI). It represents the charge carried by a proton or an electron.
The elementary charge, denoted as "e," is approximately equal to 1.602 x 10^-19 coulombs (C). By convention, the charge of a proton is considered +1e, indicating a positive charge, while the charge of an electron is considered -1e, indicating a negative charge. Other subatomic particles can have charges that are multiples or fractions of the elementary charge, such as +2e, -1/3e, and so on.
When discussing the charge of subatomic particles, it is common to refer to them in terms of their charge relative to the elementary charge. This allows for a standardized and consistent way of comparing and describing the charge of different particles.