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Showing 1681–1709 of 1709 reference entries

Measurement · PhysicsRadiant flux, intensity, irradiance, exitance and radiance

Optical power, directional power and surface densities are different quantities.

DefinitionMeasurement · PhysicsPhotometric weighting, lumen, candela, lux and luminance

Photometry weights radiation with a specified standard visual response.

DefinitionMeasurementWriting SI quantities and unit symbols

Symbol form, spacing and parentheses preserve the meaning of reported quantities.

DefinitionMeasurementGram prefixes and the kilogram exception

Mass prefixes attach to gram even though kilogram is the SI base unit.

DefinitionMeasurementRounding a result with its uncertainty

Report useful digits without treating extra digits as proof of accuracy.

MethodMeasurement · Physics · ChemistryCommon non-SI units and exact SI conversions

Common non-SI unit names require their correct SI scale factors.

DefinitionPhysics · ChemistryGas pressure as molecular momentum transfer

Molecular collisions link macroscopic pressure to random translational motion.

ModelChemistry · PhysicsOrdinary aggregate states and bulk behavior

Solid, liquid and gas describe bulk behavior rather than chemical identity.

ModelChemistryInferring empirical and molecular formulas from composition

Element mass ratios become atom ratios through molar masses, with uncertainty and sample identity retained.

MethodChemistryLewis structures and valence-electron accounting

A Lewis diagram accounts for bonding and nonbonding valence electrons in a specified connectivity.

MethodChemistryElectron-domain geometry and molecular shape

VSEPR distinguishes the arrangement of electron regions from the positions of atoms.

ModelChemistryElectronegativity, bond polarity and molecular polarity

Polar bonds can cancel in a molecule; molecular geometry matters.

ModelChemistrySolutions, solutes, solvents and solvation

Dissolution disperses specified molecular or ionic species in a solvent.

DefinitionChemistrySolubility, saturation and supersaturation

A saturation limit is an equilibrium property under specified conditions, not a synonym for concentration.

DefinitionChemistryFiltration separates retained solids from a fluid

Ordinary filtration separates undissolved particles; dissolved species can remain in the filtrate.

MethodChemistryDistillation and vapor–liquid composition

Distillation uses vapor–liquid partitioning and condensation, with a limit at an azeotrope.

MethodBiologyGene, allele, genotype and phenotype

Genomic sequence variants and observable traits describe different levels of biological information.

DefinitionBiology · ChemistryEnzyme substrates, active sites and induced fit

Substrate recognition and catalysis depend on a dynamic molecular environment.

ModelBiology · ChemistryMonomers, polymers and hydrolysis

Covalent subunit linkage and water-assisted cleavage explain biological polymer structure.

DefinitionBiology · ChemistrySugars, glycosidic linkages and polysaccharides

Sugar connectivity distinguishes energy-storage and structural polysaccharides.

DefinitionBiology · ChemistryFatty acids, storage lipids and membrane lipids

Lipids include several architectures rather than one repeating-monomer polymer class.

DefinitionBiology · ChemistryAmino-acid residues and peptide linkages

The peptide backbone and variable side chains are different parts of protein structure.

DefinitionBiology · ChemistryNucleotides and DNA/RNA backbone polarity

Bases carry sequence information on a chemically directional sugar–phosphate backbone.

DefinitionBiologyCell membrane, cell wall, cytosol and compartments

A cell's boundary, fluid interior and specialized structures have different roles.

DefinitionEarth & cosmos · MeasurementEarthquake location, source magnitude and local intensity

A source location or magnitude does not describe the shaking experienced at every site.

DefinitionEarth & cosmosAtmospheric composition and thermal layers

Composition and temperature structure describe different features of Earth's atmosphere.

ModelEarth & cosmosDrainage basins, outlets and water divides

Surface drainage boundaries depend on the chosen outlet and need not bound groundwater flow.

DefinitionEarth & cosmosThe celestial sphere and the observer's sky

A sky direction is an angular observation, not an object's three-dimensional distance.

ModelEarth & cosmos · MeasurementRight ascension, declination and reference epochs

Celestial angular coordinates require a declared reference system and date conventions.

Definition
DefinitionSource checked

Common non-SI units and exact SI conversions

MeasurementPhysicsChemistry

Common non-SI unit names require their correct SI scale factors.

Key knowledge

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.

Values and equations

1 min=60 s; 1 h=3600 s; 1 d=86400 s; 1 L=10⁻³ m³; 1 t=10³ kg; 1 eV=1.602176634×10⁻¹⁹ J

min,h,d
Minute, hour and fixed day duration unit symbols time units
L,l
Alternative litre unit symbols volume units
t
Tonne unit symbol mass unit
eV
Electronvolt unit symbol energy unit

Conditions and scope

  • Here day means the fixed unit of duration, not the variable duration of a civil day or a solar rotation interval.
  • The electronvolt conversion is exact because the elementary charge has an exact defining SI value.
  • Use min for a minute of time; the prime symbol ′ denotes a minute of plane angle.

Fresh selected BIPM bodies were inspected by the Physics/Measurement author; both documents share the same normative source family. Historical accepted-unit wording is retained in old evidence/reviews only, not adopted as the new category. Practical realization uncertainty and civil/solar day duration are outside the exact conversions.

Sources · 3

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Bureau International des Poids et Mesures (BIPM)2 sources
    1. The International System of Units, 9th edition, version 4.01 (2026)Bureau International des Poids et Mesures (BIPM)Reference guidebipm.orgRead source
    2. Updated SI Brochure clarifies the status of non-SI unitsBIPMTeaching resourcebipm.orgRead source
  2. O Sistema Internacional de Unidades (SI) · 2ª edição luso-brasileiraInmetro and Instituto Português da QualidadeReference guide · PDFgov.brRead source

Evidence and review

The SI-accepted time, volume, mass and energy units have the stated exact conversion factors.

Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged.

2026-10-10 · Independent Chemistry, Biology and Earth/Cosmos editor (AI editorial review). Source checks and independent AI editorial review of compact reference claims, equations, units, conditions and conceptual mappings. This is not human specialist certification, laboratory accreditation, whole-book verification, or a claim that all possible foundational knowledge is present.

Foundational review

2026-10-11 · Historical approval retained from its original dated scope: Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections. Continuation 2026-10-11: foundation-measurement-accepted-unit-conversions: Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged. Unchanged claim and inventory decisions are carried forward; this delta is not a new whole-field, whole-document or human certification.

Sources from other places

Scope or convention differs

Common non-SI time, volume, mass and electronvolt units have specified SI conversions; BIPM version4.01 lists them without giving them special status within the SI.

The defined day unit has a fixed seconds conversion; civil timekeeping and coherent-SI status are separate matters. Historical Brazil2012 terminology is retained as historical conversion evidence, not a normative endorsement of the2026 status category. BIPM version4.01 §4/Table8 and the2026-06-04 release support the corrected category. foundation-measurement-accepted-unit-conversions: Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–2 of 2 relationships

Scientific relationships · 2 / 2

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Uses definition
    Relationship sources · 1

    Linked statements

    • 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 numerical equalities instantiate the existing scale-factor conversion principle.

  2. Related to
    Relationship sources · 1

    Linked statements

    • 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.

Entry detailsPermanent link to this entry ↗
Record identity
foundation-measurement-accepted-unit-conversions
Revision
foundations-audit.1.continuation-20261011.1
Structured reference record
Foundational core completion