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The litre or liter (U.S. spelling, see spelling differences) is a unit of volume. There are two official symbols, the Latin letter el in both cases: l and L. The litre is not an SI unit but is accepted for use with the SI. The SI unit of volume is the cubic metre (m³). It appears in several versions of the metric system.
Definition A litre is defined as a special name for a cubic decimetre (1 L = 1 dm³). The original metric system used litres as a base unit. SI prefixes applied to the litre The litre may be used with any SI prefix. Name origin The word "litre" is derived from an older French unit, the litron, whose name came from Greek via Latin. Other common metric equivalencies Conversions One litre ≈ 0.87987699 Imperial quart Inverse: One Imperial quart ≡ 1.1365225 litres ≈ 1.056688 US fluid quarts Inverse: One US fluid quart ≡ 0.946352946 litres ≈ 1.75975326 Imperial pints Inverse: One Imperial pint ≡ 0.56826125 litres ≈ 2.11337641 US fluid pints Inverse: One US fluid pint ≡ 0.473176473 litres ≈ 0.2641720523 US liquid gallon Inverse: One US liquid gallon ≡ 3.785411784 litres ≈ 0.21997 Imperial gallon Inverse: One Imperial gallon ≡ 4.54609 litres ≈ 0.0353146667 cubic foot Inverse: One cubic foot ≡ 28.316846592 litres Rough conversions A litre is the volume of a cube with sides of 10 cm, which is slightly less than a cube of sides 4 inches (or one-third of a foot). Twenty-seven cubes "one-third of a foot on each side" would fit in one cubic foot, which is within 5% of the actual value of exactly 28.316846592 litres. One litre is also slightly more than U.S. liquid quart and slightly less than one Imperial quart or the less common U.S. dry quart. Explanation Litres are most commonly used for items measured by the capacity or size of their container (such as fluids and berries), whereas cubic metres (and derived units) are most commonly used for items measured either by their dimensions or their displacements. The litre is often also used in some calculated measurements, such as density (kg/L), allowing an easy comparison with the density of water. One litre of water has a mass of almost exactly one kilogram (1 litre of chemically pure water has a mass of 1 kg at 277.13 K (4 °C)). Similarly: 1 millilitre of water has about 1 g of mass; 1000 litres of water has about 1000 kg (1 tonne, or 1 megagram) of mass. This relationship is because the gram was originally defined as the mass of 1 mL of water. However, this definition was abandoned in 1964 because the density of water changes with pressure and the units of pressure are dependent on the definition of mass. Symbol Originally, the only symbol for the litre was l (lowercase letter l), following the SI convention that only those unit symbols that abbreviate the name of a person start with a capital letter. In many English-speaking countries, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke, that is it lacks the upstroke added in many other cultures. Therefore, the digit 1 may easily be confused with the letter l. On some typewriters, particularly older ones, the l key had to be used to type the numeral 1. Further, in some typefaces the two characters are nearly indistinguishable. This caused some concern, especially in the medical community. As a result, L (uppercase letter L) was accepted as an alternative symbol for litre in 1979. The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L, a practice that is also widely followed in Canada and Australia. In these countries, the symbol L is also used with prefixes, as in mL and µL, instead of the traditional ml and µl used in Europe. In Britain and Ireland, lowercase l is used with prefixes, though whole litres are often written in full (so, "750 ml" on a wine bottle, but often "1 litre" on a juice carton). Prior to 1979, the symbol & History In 1793, the litre was introduced in France as one of the new "Republican Measures", and defined as one cubic decimetre. In 1879, the CIPM adopted the definition of the litre, and the symbol l (lowercase letter l). In 1901, at the 3rd CGPM conference, the litre was redefined as the space occupied by 1 kg of pure water at the temperature of its maximum density (3.98 °C) under a pressure of 1 atm. This made the litre equal to about 1.000 028 dm³ (earlier reference works usually put it at 1.000 027 dm³). In 1964, at the 12th CGPM conference, the original definition was reverted to thus the litre was once again defined in exact relation to the metre, as another name for the cubic decimetre, that is, exactly 1 dm³. • In 1979, at the 16th CGPM conference, the alternative symbol L (uppercase letter L) was adopted. It also expressed a preference that in the future only one of these two symbols should be retained, but in 1990 said it was still too early to do so.• Colloquial Usage In spoken English, the abbreviation "mL" (for millilitre) is often pronounced as mil. The abbreviation cc (for cubic centimetre) is also used colloquially, especially in the medical field. See also | ||||||||
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