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What is an Angstrom?

In 1868, a Swedish Physicist named Anders Jonas Ångström (a founder of Spectroscopy) created a chart of the spectrum of sunlight in which he expressed the wavelengths in multiples of one ten-millionth of a millimetre, i.e., 10E−7 mm. 

Ångström's chart and table of wavelengths in the solar spectrum are widely used in solar physics, which adopted the unit and named it after him and the Angstrom symbol is Å.

In this article, we will learn the Angstrom definition and study the angstrom value in detail.

What Did We Understand?

The angstrom (ångström) is a metric unit of length that is equal to 10 m.

1 angstrom is one ten-billionth of a meter 0.1 nanometre or 100 picometres. 

The symbol for the Angstrom unit is Å,  which is a letter of the Swedish alphabet.

History of Angstrom Unit

The Angstrom unit was precisely defined by its own standard because it bears a very small value. 

The error in the meter standard was larger than the angstrom unit. 

According to the 1907 definition, the angstrom was the wavelength of the red line of cadmium, equal to 6438.46963 international ångströms. 

In 1960, the standard for the meter was restated in terms of spectroscopy, finally considering the two units on the same definition/understanding.

Angstrom Definition

The angstrom unit is a measure of displacement that is equal to 0.0000000001 meters or 10\[^{-10}\]m (angstrom measure). 

Angstrom is sometimes used to express wavelengths of visible light, ultraviolet aka UV light, X rays and gamma rays.

The visible-light spectrum extends from approximately 7700 angstroms (i.e.,  from red light to 3900 angstroms to violet light).

This pertains to frequencies of 390 to 770 THz (Tetra Hertz), where 1 THz = 10^12 Hz. Ultraviolet (UV) radiation, X rays, and gamma rays have shorter wavelengths and higher frequencies, respectively. Some gamma rays have wavelengths less than 0.0001 or 10-4angstrom.

However, the angstrom unit is not often used nowadays. Now, it has been largely superseded by the nanometer (nm), which is 10 times larger; 1 nm = 10 angstroms = 10\[^{-9}\] m.


Angstrom Unit of Measure

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Fun Fact

We must know that ångström is not a part of the SI system of units; however, we can consider it as part of the metric system in general.

The Angstrom unit was used for X-ray wavelengths around 1900 when X-rays were first discovered. 

However, it was replaced by a set of standards for units that required the use of unit space every 1000. 

Wavelengths were in meters, mm, microns, nano, etc

Angstrom To Meter Conversion Data

Do you know how to convert Angstrom to Meter?


Below are some examples to solve the conversion of Angstrom Unit To Meter Unit:

  1. 0.01  Å =  1.0 E- 12 m

  2. 0.1 Å = 1.0 E - 11 m

  3. 1 Å = 1.0 E - 10 m

  4. 2 Å = 2.0 E - 10 m

  5. 3 Å = 3.0 E - 10 m

  6. 5 Å = 5.0 E - 10 m

  7. 10 Å = 1.0 E - 9 m

  8. 20 Å = 2.0 E - 9 m 

  9. 50 Å = 5.0 E - 9 m

  10. 100 Å = 1.0 E - 8 m

  11. 1000 Å = 1.0 E - 7 m

Now, let’s solve consider an example to understand the conversion:

The formula for the conversion of Angstrom to Meter is:

1 A = 1.0 E-10 m

1 m = 10000000000 A

For example: convert 18 A to m

18 A = 18 × 1.0 E - 10 m 

So, the Angstrom value is 1.8E - 9 m


Is Angstrom Unit Still in Use?

No, the Angstrom unit is not in use. The reason for the same is mentioned below:

The angstrom served its purpose and is widely used in some technical fields.

As early as 1978, the International Committee for Weights and Measure called for the stopping the use of this unit of measurement by requesting scientists refrain from applying the angstrom to new applications/fields where it was not in use. The American National Standard for Metric Practice also discouraged its use and today the angstrom is considered an obsolete unit.

Although Armstrong Length is deprecated by both the International Bureau of Weights and Measures (BIPM) and the US National Institute of Standards and Technology (NIST), the unit is still used in the natural sciences and technology in the following ways:

  1. To express sizes of atoms, and molecules

  2. To express microscopic biological structures, 

  3. Lengths of chemical bonds, and 

  4. The arrangement of atoms in crystals

From the above text, we found the Angstrom Unit is not much used;  however, we find its applications in many scientific fields. 

FAQ (Frequently Asked Questions)

Question 1: What is an Armstrong Number?

Answer: An Armstrong number is a number whose sum of cubes of each digit becomes equal to the number itself.

1. Let’s suppose that 153 is a number and now we will do the cube of each digit in the following way:

1 * 1 * 1 = 1

5 * 5 * 5 = 125

3 * 3 * 3 = 27

Now, summing up these numbers:

1 + 125 + 27

We get the Armstrong number as 153 again.


2. Let’s take another look at an Armstrong number:


3 * 3 * 3 = 27

7 * 7 * 7 = 343

1 * 1 * 1 = 1

Now, summing up these numbers:

27 + 343 + 1 

We get the Armstrong number as 371 again.

Question 2: Describe One Use of Angstrom Unit.

Answer: The diameter of an atom is of the order 1 angstrom, so the unit is particularly easy-to-understand when pertaining to the atomic and ionic radius/the size of molecules, and spacing between atoms in crystals. 


The covalent radius of atoms like sulfur, chlorine and phosphorus is also about one angstrom, while the size of a hydrogen atom is about half of an angstrom. 


The angstrom is used in the field of solid-state Physics, Chemistry, and Crystallography. The unit is used to determine wavelengths of light, chemical bond length, and the size of microscopic structures using the electron microscope. X-ray wavelengths can also be given in angstroms, as these values usually range from 1 to 10 Å.