International Committee for Weights and Measures

The International Bureau of Weights and Measures is the English name of the Bureau international des poids et mesures (BIPM, often written in English Bureau International des Poids et Mesures), a standards organization, one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention). Note that the abbreviation IBWM does not exist. It is based at th ...

Read more here: » International Bureau of Weights and Measures: Encyclopedia - International Bureau of Weights and Measures

The metric system was officially adopted in France after the French Revolution. During the history of the metric system a number of variations have evolved and their use spread around the world replacing many traditional measurement systems. By the end of World War II a number of different systems of measurement were still in use throughout the world. Some of these systems were metric system variations whilst others were based on the Imperial and American systems. It was recognised that additional steps were needed to promote a worldw ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues

Read more here: » SI: Encyclopedia II - SI - History

Decibel - Acoustics. The decibel unit is often used in acoustics to quantify sound levels relative to some 0 dB reference. The reference may be defined as a sound pressure level (SPL), commonly 20 micropascals (20 μPa). To avoid confusion with other decibel measures, the term dB(SPL) is used for this. The reference sound pressure (corresponding to a sound pressure level of 0 dB) can also be defined as the sound pressure at the threshold of human hearing, which is conventionally taken to be 2×10−5 newtons per square metre, or 20 micropascals. That is roughly the soun ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - dB cheat sheet, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Uses

The metric system was created during the French Revolution. On August 1, 1793 the National Convention adopted the new decimal "metre" with a provisional length as well as the other decimal units with preliminary definitions and terms. On April 7, 1795 (Loi du 18 germinal, an III) the terms gramme and kilogramme repaced the former terms "gravet" and "grave". After the 18 Brumaire Year VIII, the metric system was definitively adopted in France by the First Consul Bonaparte, (the later Napoleon I) on Decembre 10, 1799 (Loi ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues, SI - Trade

Read more here: » SI: Encyclopedia II - SI - History

Decibel - Acoustics. The decibel unit is often used in acoustics to quantify sound levels relative to some 0 dB reference. The reference may be defined as a sound pressure level (SPL), commonly 20 micropascals (20 μPa). To avoid confusion with other decibel measures, the term dB(SPL) is used for this. The reference sound pressure (corresponding to a sound pressure level of 0 dB) can also be defined as the sound pressure at the threshold of human hearing, which is conventionally taken to be 2×10−5 newtons per square metre, or 20 micropascals. That is roughly the soun ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Uses

The swift worldwide adoption of the metric system as a tool of economy and everyday commerce was based mainly on the lack of customary systems in many countries to adequately describe some concepts, or as a result of an attempt to standardize the many regional variations in the customary system. International factors also affected the adoption of the metric system, as many countries increased their trade. Scientifically, it provides ease when dealing with very large and small quantities because it lines up so ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues, SI - Trade

Read more here: » SI: Encyclopedia II - SI - Cultural issues

An intensity I or power P can be expressed in decibels with the standard equation where I0 and P0 are a specified reference intensity and power. If PdB is 10 dB greater than PdB0 then P is ten times P0. If PdB is 3 dB greater, the power r ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - dB cheat sheet, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Definition

SI - Spelling variations. Several nations, notably the United States, typically use the spellings 'meter' and 'liter' instead of 'metre' and 'litre' in keeping with standard American English spelling. In addition, the official US spelling for the SI prefix 'deca' is 'deka'. The unit 'gram' is also sometimes spelled 'gramme' in English-speaking countries other than the United States, though that is an older spelling and its use is declining. ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues, SI - Trade

Read more here: » SI: Encyclopedia II - SI - SI writing style

Decibel - Absolute measurements. dBm or dBmW  dB(1 mW) — power measurement relative to 1 milliwatt. dBW  dB(1 W) — same as dBm, with reference level of 1 watt. dBu or dBv  dB(0.775 V) — (usually RMS) voltage amplitude referenced to 0.775 volt. Although dBu can be used with any impedance, dBu = dBm when the load is 600Ω. dBu is preferable, since dBv is easily confused with dBV. The "u" comes from "unlo ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - dB cheat sheet, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Typical abbreviations

Decibels are handy for mental calculation, because adding them is easier than multiplying ratios. First, however, one has to be able to convert easily between ratios and decibels. The most obvious way is to memorize the logs of small primes, but there are a few other tricks that can help. Decibel - Round numbers. The values of coins and banknotes are round numbers. The rules are: One is a round number Twice a round number is a round number: 2, 4, 8, 16, 32, 64 Ten times a rou ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - dB cheat sheet, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Reckoning

A bel (symbol B) is a unit of measure of ratios, such as power levels and voltage levels. It is mostly used in telecommunication, electronics, and acoustics. Invented by engineers of the Bell Telephone Laboratory to quantify the reduction in audio level over a 1 mile length of standard telephone cable, it was originally called the transmission unit or TU, but was renamed in 1923 or 1924 in honor of the laboratory's found ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - dB cheat sheet, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - History of bels and decibels

The swift worldwide adoption of the metric system as a tool of economy and everyday commerce was based mainly on the lack of customary systems in many countries to adequately describe some concepts, or as a result of an attempt to standardize the many regional variations in the customary system. International factors also affected the adoption of the metric system, as many countries increased their trade. Scientifically, it provides ease when dealing with very large and small quantities because it lines up so ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues

Read more here: » SI: Encyclopedia II - SI - Cultural issues

Decibel - Absolute measurements. dBm or dBmW  dB(1 mW) — power measurement relative to 1 milliwatt. dBW  dB(1 W) — same as dBm, with reference level of 1 watt. dBu or dBv  dB(0.775 V) — (usually RMS) voltage amplitude referenced to 0.775 volt. Although dBu can be used with any impedance, dBu = dBm when the load is 600Ω. dBu is preferable, since dBv is easily confused with dBV. The "u" comes from "unlo ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Typical abbreviations

A bel (symbol B) is a unit of measure of ratios, such as power levels and voltage levels. It is mostly used in telecommunication, electronics, and acoustics. Invented by engineers of the Bell Telephone Laboratory to quantify the reduction in audio level over a 1 mile length of standard telephone cable, it was originally called the transmission unit or TU, but was renamed in 1923 or 1924 in honor of the laboratory's found ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - History of bels and decibels

Decibels are handy for mental calculation, because adding them is easier than multiplying ratios. First, however, one has to be able to convert easily between ratios and decibels. The most obvious way is to memorize the logs of small primes, but there are a few other tricks that can help. Decibel - Round numbers. The values of coins and banknotes are round numbers. The rules are: One is a round number Twice a round number is a round number: 2, 4, 8, 16, 32, 64 Ten times a rou ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Reckoning

The international system of units consists of a set of units together with a set of prefixes. The units of SI can be divided into two subsets. There are the seven base units. Each of these base units are dimensionally independent. From these seven base units several other units are derived. In addition to the SI units there are also a set of non-SI units accepted for use with SI. A prefix may be added to units to produce a multiple of the original unit. All multiples are integer powers of ten. For example, kilo- denotes a multi ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues

Read more here: » SI: Encyclopedia II - SI - Units

An intensity I or power P can be expressed in decibels with the standard equation where I0 and P0 are a specified reference intensity and power. If PdB is 10 dB greater than PdB0 then P is ten times P0. If PdB is 3 dB greater, the power r ...

See also:

Decibel, Decibel - Definition, Decibel - Standards, Decibel - Merits, Decibel - History of bels and decibels, Decibel - Uses, Decibel - Acoustics, Decibel - Electronics, Decibel - Optics, Decibel - Telecommunications, Decibel - Seismology, Decibel - Typical abbreviations, Decibel - Absolute measurements, Decibel - Relative measurements, Decibel - Reckoning, Decibel - Round numbers, Decibel - The 4 → 6 energy rule, Decibel - The 789 rule, Decibel - −3 dB ≈ ½ power, Decibel - 6 dB per bit, Decibel - Reference

Read more here: » Decibel: Encyclopedia II - Decibel - Definition

SI - Spelling variations. Several nations, notably the United States, typically use the spellings 'meter' and 'liter' instead of 'metre' and 'litre' in keeping with standard American English spelling. In addition, the official US spelling for the SI prefix 'deca' is 'deka'. The unit 'gram' is also sometimes spelled 'gramme' in English-speaking countries other than the United States, though that is an older spelling and its use is declining. ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues

Read more here: » SI: Encyclopedia II - SI - SI writing style

The international system of units consists of a set of units together with a set of prefixes. The units of SI can be divided into two subsets. There are the seven base units. Each of these base units are dimensionally independent. From these seven base units several other units are derived. In addition to the SI units there are also a set of non-SI units accepted for use with SI. A prefix may be added to units to produce a multiple of the original unit. All multiples are integer powers of ten. For example, kilo- denotes a multi ...

See also:

SI, SI - History, SI - Units, SI - SI writing style, SI - Spelling variations, SI - Cultural issues, SI - Trade

Read more here: » SI: Encyclopedia II - SI - Units