|standard||SI fundamental unit|
|in SI-UNITs||SI fundamental unit|
|designated after||griech. métron, measure|
of the meters (v. griech.: μέτρον/métron = measure, - measurers) - according to Duden also meters, in Switzerland and Austria always the meter - those is SI - fundamental unit of the length. The unit symbol of the meter reads m and the symbol of the length l.
Table of contents
of the meters is defined when the distance, which puts the light back in the vacuum in a time of 1/299.792.458 second. To the conversion of the length of a standardized dipstick upare based came it, because the measurement of times takes place in the meantime substantially more exactly, as the measurement of lengths.
old persons definitions
of the definition of the meter preceded some suggestions to define a universal unit of length the non howat that time usually - from the dimensions of the member masses of the respective ruler was derived. Thus the abbott Jean Picard suggested for example 1668 using as unit of length the length of a pendulum which had a half period duration of one second (Second pendulum). Such a pendulum has the length of 0,994 m and would approximate thereby the today's definition of a meter quite. The term meter for this unit of length was used however for the first time by Tito Livio Burattini in the year 1675.It called the length of the second pendulum Metro Cattolico (catholic meter).
In the year 1793 the meter became then as the 40-millionste part of the length of the Erdmeridians, on which Paris lies, thus fixed on the zehnmillionsten part of the distance of the pole to the equator. In the year 1795 a prototype of this meter was finally poured in brass, in the year 1799 as Urmeter in platinum. To the regulationthe results of the measurement of the Meridianbogens between you churches and Barcelona, made by Jean Baptiste Joseph Delambre and Pierre Méchain between 1792 and 1799, served the length of the Urmeters. More exact measurements of the earth came later however to the result that thatUrmeter was a little too briefly guessed/advised.
1889 were introduced by in the meantime created BIPM a new standard. In addition the international meter prototype was made, a staff with cross-shaped cross section from to platinum - iridium - an alloy in the relationship 90:10 andMeter fixed as the distance of the central lines of two groups of lines at a temperature of 0 °C. Thus meter did not depend any longer on the measurement of the earth. Copies of this meter prototype were assigned to the calibration institutes in many countries.
From 1960 to 1983 that was meter 1.650.763, 73-fache of the wavelength of the radiation spreading in the vacuum, which is sent by atoms of the nuclide krypton -86 with the transition of the condition 5d5 to the condition 2p10.
Since 1983 that becomes meterwhen the distance defines, which puts the light back in the vacuum in a time of 1/299.792.458 second. The reason for this redefinition is that meanwhile the time (with atomic clocks) is many more exactly measurable than distances. This has also as a consequence,the fact that the speed of light does not have to be measured now any longer but as constant is fixed with 299.792.458 m/s.
multiple and fractions
in the following are described some examples of different lengths. To the prefixes see also the list to thatPrefixes for units.
|factor||10 24||10 21||10 18||10 15||10 12||10 9||10 6||10 3||10 2||10 1|
|factor||10 -1||10 -2||10 -3||10 -6||10-9||10 -12||10 -15||10 -18||10 -21||10 -24|
A kilometer, shortened km, corresponds 1,000 meter: 1 km = 10 3 M.
A Dezimeter, shortened DM, corresponds to thatTenth one meter or 0.1 M.
A centimeter (also Centimeter becomes outdated), shortened cm, corresponds the hundredth of a meter: 1 cm = 10 -2 m or 0.01 M. A centimeter corresponds likewise to the tenth of a Dezimeters: 1 cm= 0.1 DM.
A millimeter, shortened mm, corresponds the thousandth of a meter: 1 mm = 10 -3 m or 0.001 M.
A micrometer (also Micron , or My becomes outdated after the Greek letter µ), shortened µm, corresponds the millionth of a meter: 1 µm = 10 -6 m = 0.000 001 M. Or 1 µm = 10 -3 mm, thus a thousandthMillimeter.
My designates beyond that in the colloquial use often smallest lengths, which are still recognizable straight, although a micrometer cannot be noticed actually with free eye.
The micrometer screw, a linear measuring instrument, becomes because of their accuracy often micrometer screw or briefly Micrometer mentioned.
A nanometer, shortened Nm, corresponds the billionth of a meter: 1 Nm = 10 -9 M. Or 1 Nm = 10 -6 mm, thus a millionth millimeter.
A nanometer corresponds to one in a piece metal approximatelyDistance of four neighbouring atoms. The smallest structures recognizable with an optical microscope are about 500 Nm largely. For the investigation of structures below 500 Nm uses one scanning electron microscopes, raster tunnel microscopes or raster force microscopes.
See also: Nano-technology
A Pikometer (becomes outdated also pico-meter), shortened pm, corresponds the trillionth of a meter: 1 pm = 10,-12 M.
A Femtometer (unit symbol: FM), is the Billiardstel meters: anda trillionth of a millimeter of 1 FM = 10,-15 M.
The Femtometer was called in former times in the atomic and nuclear physics also Fermi; its use leads to clear numerical values with the indication of atomic nucleus diameters. Because the diameter of an atomic nucleusabout 10 amounts to FM.Protons and neutrons have a diameter of approximately 1.6 FM. The smallest atomic radii measure 51000 FM = 51 pm.
a Myriameter corresponds 10,000 meters. Die Maßeinheit Myriameter wurde zum Beispiel im sächsischen Eisenbahnbau undfor the Kilometrierung of the Rhine uses. Both on the Rhine as for instance also at the route of the wind mountain railway shut down today is still received Myriametersteine.
a Hektometer (unit character: TC) corresponds 100 meters. This unit becomes in the artillery nature for the weapon range(Range of fire) uses.
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|Wiktionary: Meter - word origin, synonyms and translations|