Angstroms to Kilometers
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1 angstrom (Å) = 1E-13 kilometer (km). Angstrom (Å) is a unit of Length used in Metric system. Kilometer (km) is a unit of Length used in Metric system.

Angstrom: A Small Unit of Length Used in the SI System

The angstrom is a unit of length that is equal to 0.1 nanometer (nm) or 10^-10 meter (m). It is one of the non-SI units that are accepted for use with the International System of Units (SI), which is the most widely used system of measurement in the world. The symbol for angstrom is Å, a letter of the Swedish alphabet. The unit is named after the Swedish physicist Anders Jonas Ångström (1814-1874), who was a pioneer in the field of spectroscopy. The angstrom is often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. In this article, we will explore the definition, history, usage and conversion of the angstrom as a unit of length.

Definition of the Unit

The angstrom is a unit of length that is equal to 0.1 nanometer (nm) or 10^-10 meter (m). It is one of the non-SI units that are accepted for use with the International System of Units (SI), which is based on seven base units: meter (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance) and candela (luminous intensity). The SI base unit of length is the meter, which is defined as the length of the path travelled by light in vacuum during a time interval of 1/299792458 seconds.

The definition of the angstrom has not changed since its introduction in 1868 by Anders Jonas Ångström, who used it to express wavelengths of light in his chart of the spectrum of sunlight. However, the definition of the meter has changed several times over time, as different standards and methods of measurement were adopted by various countries and regions. The current definition of the meter as based on the speed of light was agreed upon by an international treaty in 1983, and since then the angstrom has been exactly equal to 10^-10 meter.

History of the Unit

The origin of the angstrom as a unit of length can be traced back to 1868, when Swedish physicist Anders Jonas Ångström created a chart of the spectrum of sunlight, in which he expressed the wavelengths of electromagnetic radiation in multiples of one ten-millionth of a millimeter (or 10^-7 mm). He chose this unit because it was convenient for his work on spectroscopy, which is the study of how matter interacts with electromagnetic radiation. He also named this unit after himself, as he wrote in his paper: "I have taken as unit for these measurements one ten-millionth part [of a millimeter], which I will call an Ångström".

Ångström’s unit was soon adopted by other spectroscopists and physicists, who found it useful for expressing wavelengths of visible light, ultraviolet light and X-rays. However, they soon realized that the definition of the millimeter at the time, based on a material artifact, was not accurate enough for their work. So, around 1907 they defined their own unit of length, which they called "Ångström", based on the wavelength of a specific spectral line emitted by krypton-86 gas. This new definition was more precise and stable than the previous one based on the millimeter.

In 1960, when the meter was redefined as based on a specific number of wavelengths emitted by krypton-86 gas, the angstrom became again equal to 10^-10 meter. However, this definition was soon replaced by another one based on the speed of light in vacuum in 1983. Since then, the angstrom has remained unchanged as equal to 10^-10 meter.

Usage of the Unit

The angstrom is a unit of length that is often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. Some examples of where the angstrom is used are:

• Chemistry: The angstrom is used for measuring atomic radii, bond lengths and interatomic distances. For example, a carbon atom has an atomic radius of about 0.77 Å, a carbon-carbon single bond has a length of about 1.54 Å, and a benzene molecule has a diameter of about 5.4 Å.
• Biology: The angstrom is used for measuring molecular structures, such as proteins, DNA and viruses. For example, a typical amino acid has a size of about 3 Å, a DNA helix has a diameter of about 20 Å, and a coronavirus has a diameter of about 120,000 Å.
• Physics: The angstrom is used for measuring wavelengths of electromagnetic radiation, such as visible light, ultraviolet light and X-rays. For example, the visible spectrum ranges from about 4000 Å (violet) to 7000 Å (red), the ultraviolet spectrum ranges from about 10 Å to 4000 Å, and the X-ray spectrum ranges from about 0.01 Å to 10 Å.
• Engineering: The angstrom is used for measuring dimensions of integrated circuit parts, such as transistors, wires and gates. For example, the smallest feature size of a modern microprocessor is about 50 Å.

How to Convert

The angstrom can be converted to other units of length by using conversion factors or formulas. Here are some examples of how to convert angstroms to other units of length in the U.S. customary system, the imperial system and the SI system:

• To convert angstroms to inches, divide by 2.54 × 108. For example, 100 Å = 100 / (2.54 × 108) = 3.937 × 10^-7 in.
• To convert angstroms to feet, divide by 3.048 × 109. For example, 1000 Å = 1000 / (3.048 × 109) = 3.281 × 10^-8 ft.
• To convert angstroms to yards, divide by 9.144 × 109. For example, 10,000 Å = 10,000 / (9.144 × 109) = 1.094 × 10^-8 yd.
• To convert angstroms to miles, divide by 1.609 × 1013. For example, 100 million Å = 100 million / (1.609 × 1013) = 6.214 × 10^-6 mi.
• To convert angstroms to centimeters, divide by 108. For example, one angstrom = one / (108) = one-hundred-millionth of a centimeter.
• To convert angstroms to meters, divide by 1010. For example, one angstrom = one / (1010) = one-ten-billionth of a meter.

Kilometer - Unit of Distance / Length

Unit Symbol/Abbreviation: km

Where the unit used in the World:

The kilometer is used as a unit used to measure distances or lengths.
It's a standard measure for travelled distances, geographical distances and maps in most countries excluding the USA and the United Kingdom where mile is still used for this purpose.
between geographical locations on land, and in most countries is the official unit for this purpose. Primary exceptions are the United Kingdom, Liberia, Myanmar and the United States of America, where the mile remains as standard as a part of imperial system.

Definition of the Unit:

The kilometer (kilometre in UK spelling) is a unit of length/distance in the metric system (SI Unit system) equivalent to one thousand meters.

1 km is equivalent to 0.62137 miles.

History of the Unit:

Although the meter was defined in 1799 in France, the kilometer was first adopted for everyday use by the Dutch in 1817 under local name of the mijl. The myriametre (10000 meters) and "lieues de Poste" (Postal leagues, 4288 meters) were preferred to the "kilometer" for everyday use in France in 19th century. In the mid 19th century the kilometer was already in everyday use in the Italy and in Netherlands and the myriametre was still in use in France. The CIPM (The International Committee for Weights and Measures) officially abolished the prefix "myria-" and the "myriametre" in 1935, leaving the kilometer as the recognised unit of length instead of myriametre.

Where it's used:

The kilometer is commonly used on road signs to indicate the distance to travel to a given location, on maps to indicate scale, for odometer indication in automotive industry. It is also the most popular unit for describing the distance between geographical points and locations.

Equivalents in other units and scales:

• 1 km = 1000000 millimeters (mm)
• 1 km = 100 000 centimeters (cm)
• 1 km = 10000 decimeters (dm)
• 1 km = 1000 meters (m)
• 1 km = 3280.84 feet (ft)
• 1 megameter = 1000 km
• 1 gigameter = 1000000 km
• 1 mile = 1.609 km
• 1 yard = 0.000914 km
• 1 foot = 0.000305 km
• 1 inch = 0.0000254 km
• Units of length in the metric SI system are based on multiples or fractions of a meter.
• There are measurements of length/distance in the metric SI system greater than a kilometer that can be expressed in terms of kilometres.

1 km is equivalent to 0.621371 mi.

The kilometer is unit of length in the metric SI system and is equivalent to one thousand metres.