1 decimeter = 0.000 1 km = 0. 1 meter (m) =10cm = 100 mm (mm);

1cm =10mm = 0.1decimeter = 0.01m = 0.00001km;

1mm = 0.1cm = 0.01decimeter = 0.001m = 0.000001km;

1 micron = 1 000 nm = 0.00 1 mm = 0.000 1 cm;

1nm = 0.00000 1mm；

1 picometer =10-12m = 0.001nanometer (nm) = 0.0000 1 micron (micron).

The negative power of a number is the reciprocal of the positive power of this number.

a^-x= 1/a^x

For example: 0 power of -65438+2 = 1/2 power.

1/2-1 power =2.

The 5th power of -2 =1/5th power,

1/5 -2 =5-2.

Extended data:

Commonly used length units are: kilometer {kilometer} (km), decimeter (dm), centimeter (cm), millimeter (mm), micron (micron), nanometer (nm), picometer (pm) and femto meter (fm).

(1) km

Kilometer, also known as kilometer, is a unit of length, abbreviated as "km", which is usually used to measure the distance between two places. The common conversion relationship is as follows: 1 km (km) = 1 0,000m (m) = 1 00,000m (cm) =10,000mm (mm); 1.6 1 km = 1 mile.

(2) meters

The unit of length "meter" in the international system of units originated in France. 1790 in may, a special Committee composed of French scientists suggested that one fortieth of the total length of the earth meridian passing through Paris should be used as the unit of length.

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M, 179 1 was approved by the French parliament.

In order to make a benchmark to represent the value of rice, under the leadership of French astronomers Gerliangbule and Mishin, measurements were made from Dunkirk, France to Barcelona, Spain, and from 1792 to 1799.

1799 according to the measurement results, a short-section platinum rod of 3.5mm× 25mm was made.

Meter pole), the distance between the two ends of this pole is set as 1 meter, which is kept by the French archives, so it is also called "archival meter". This is the earliest definition of rice.

Due to the serious deformation of archival rice, 1872 abandoned the definition of archival rice and used rice made of original platinum alloy (90% platinum, 10% iridium) as the length unit.

The original rice cooker was made according to the length of the "file rice". At that time, * * * made 3 1 piece, the cross section was approximately X-shaped, and the length of the archive meter was engraved on the groove (neutral surface) of the ruler with two 6-8 micron wide scribes.

1889 At the first international metrology conference, the No.6 rice field identified by the International Bureau of Metrology (3 1 rice field is the closest to the 0℃ length of the archival rice field) was selected as the international rice field, which was kept as the longest length benchmark in the world in the basement of the International Bureau of Metrology in Paris, and the remaining rulers were distributed to the participating countries as auxiliary rulers. When the ambient air temperature is 0℃, the distance between the two ends of the rice cooker is1m.

1927 the seventh international metrology congress made strict regulations on the definition of rice. In addition to the temperature requirement, it is also proposed that the raw rice container should be kept at the standard atmospheric pressure 1, and its placement method is specified in detail.

However, there are many shortcomings in taking rice as the objective standard of rice, such as material deformation; The measurement accuracy is not high (only 0. 1μm). It is difficult to meet the needs of precise measurement such as metrology.

In addition, if the original rice cooker is damaged, there will be no basis for copying, especially it is difficult to ensure that the replica is completely consistent with the original rice cooker, which brings difficulties to the use of various countries. Therefore, the idea of using natural values as unit benchmarks has always been desired by people. In 1950s, with the development of isotope spectrum light source.

The narrow Krypton -86 isotope spectrum was discovered. With the success of interference technology, people finally found a natural standard that is not easy to be destroyed, that is, the natural standard with the wavelength of light wave as the length unit.

This natural benchmark has stable performance, no deformation problem, easy replication and high replication accuracy. China also established the krypton -86 isotope length standard in 1963.

After the definition of rice is changed, the original international rice instruments are still kept in the International Bureau of Metrology according to the original regulations. With the progress of science and technology, since the 1970s, the measurement of time and the speed of light has reached a high precision.

Therefore, 1983, 10 adopted a new definition of the meter at the 17th international metrology conference held in Paris in June: "the meter is the length of light propagating in a vacuum with a time interval of 1/299792458 seconds". In this way, the definition of meter based on spectral line wavelength is replaced by the new definition of meter.

(3) decimeter

Decimeter or dm is one of the metric units of length, and 1 decimeter is equivalent to one tenth of 1 meter. The common conversion relationship is as follows: 1 decimeter = 0.000 1 kilometer (km) = 0. 1 meter (m) = 10 centimeter (cm) = 100 millimeter (mm).

4) cm

Centimeter, unit of length; Chinese: centimeter (s), abbreviated as cm. The unit conversion of centimeters is as follows:1cm =10 mm = 0.1decimeter = 0.0 1 m = 0.0000 1 km.

(5) mm

Millimeter, also known as millimeter (or millimeter), is a unit of length and rainfall, and the symbol is ㎜. 1mm is equivalent to one thousandth of 1mm (this means "milli"). The decimal relation is as follows:1mm = 0.1cm = 0.01decimeter = 0.001m = 0.000001km.

(6) Micron

Micron is a unit of length, and the symbol [micron] is pronounced [miú]. 1 micron is equivalent to one millionth of 1 meter (which means "micro"). The conversion relationship is as follows: 1 micron (micron) = 1 000 nanometer (nanometer) = 0.00 1 millimeter (millimeter) = 0.000 1 cm.

(7) Nanometer

Nanometer (symbol is nm) is the unit of length, originally called nanometer, that is, 10-9 meters (65438+ billionth of a meter). Like centimeters, decimeters and meters, it is a unit of measurement for length. It is four times the size of an atom and less than the length of a single bacterium. A single bacterial microorganism is invisible to the naked eye, and the diameter measured by a microscope is about five microns, which is five thousand nanometers.

For example, suppose that the diameter of a hair is 0.05 mm, and it is cut into 50,000 pieces on average in the radial direction, and the thickness of each piece is about one nanometer. That is to say, one nanometer is about 0.000001mm. Nanoscience and technology, sometimes called nanotechnology, is to study the properties and applications of materials with structural dimensions ranging from 1 to 100 nm.

(8) Pimi (pm)

Pimi or pm is the unit of length, and 1 pimi is equivalent to one trillion of 1 meter. Sometimes it is called a micron in atomic physics. The conversion relationship is as follows: 1 picometer =10-12m = 0.001nanometer (nm) = 0.0000 1 micron (micron).

References:

Negative forces-Baidu Encyclopedia

Length unit-Baidu Encyclopedia