BIPM defining-constant table; NIST elementary-charge value and unit.
2026-10-10 · Exact value, symbol and coulomb unit only.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Agreement within this scope
The elementary charge magnitude has exact SI value 1.602176634×10−19 C.
Electron charge is negative; e denotes the positive magnitude.
For ordinary atomic matter with N_p protons and N_e electrons, net electric charge is Q=e(N_p−N_e). Equal counts give zero net charge, while an excess of electrons gives negative charge. Neutrality does not mean that constituent charges or all local electric fields disappear; separating charges changes the distribution while preserving total charge in an isolated system.
This relation concerns the stated atomic net charge and electrical neutrality claim and its conditions; it does not assert an unqualified prerequisite or an additional theorem.
Vector current density J gives current I=∫J·n dA across an oriented surface. For one carrier species of signed charge q and number density n_c, its drift contribution is J=n_cqv_d; contributions from species add. Random microscopic velocity is not the same as net drift, and negative carriers drifting one way give conventional current in the opposite direction.
This relation concerns the stated current density and carrier drift claim and its conditions; it does not assert an unqualified prerequisite or an additional theorem.
For one-photon emission from a specified surface with work function Φ, maximum initial electron kinetic energy is K_max=hf−Φ when hf≥Φ. An ideal stopping-potential magnitude V_stop satisfies eV_stop=K_max, and threshold frequency is Φ/h. At fixed frequency and surface state in this regime, increasing intensity increases the number/rate of photoelectrons rather than this maximum energy.
This relation concerns the stated photoelectric threshold and stopping potential claim and its conditions; it does not assert an unqualified prerequisite or an additional theorem.
The minute, hour and day correspond to 60 s, 3600 s and 86400 s. The litre is exactly 10⁻³ m³, the tonne is 1000 kg, and the electronvolt is exactly 1.602176634×10⁻¹⁹ J. These commonly used non-SI units are listed with SI conversions; inclusion gives them no special status within the SI and does not make them coherent SI units. Both l and L are allowed litre symbols.
The exact elementary-charge value fixes the electronvolt-to-joule factor.