Unit of Length

Length

The measurement of something from one end to the other is called length. In other words, the length of anything determines how lengthy it is. In the International System of Quantities, it is defined as a quantity of dimension distance.

In a vacuum, the length of the path travelled by light in 1/299792458 seconds.

SI Unit of Length

The metre is the SI unit of length measurement (m). The metre is the base unit of length, as seen in the graph above. The following are its values in different units:

• 1 m = 100 cm 
• 1 m = 1000 mm 
• 1 m = 0.001 km 
• 1 m = 39.37 inches 
• 1 m = 1.09361 yards 
• 1 m = 3.28 feet 

Types of Lengths

• Measuring Long Distance Lengths: –

Some objects, such as the sun and stars, are so far away from the planet that their distance cannot be measured using a scale. One of the most common methods for measuring it is parallax. The angle or semi-angle of inclination between two lines of sight is used to quantify parallax, which is a displacement or difference in the apparent position of an object viewed along two different lines of sight. The Basis is the distance between the two views.

• Measuring Short Distance Length: –

To measure very small sizes, such as those of a molecule, special procedures must be used (10-8m –10-10m). It’s too little to be measured with a microscope. The wavelength range for visible light is around 4000 Å to 7000 Å (1Å=10-10m). Even an optical microscope can’t measure particles smaller than this. 

Instead of visible light, electron beams can be employed. The employment of appropriately constructed electric and magnetic fields helps focus electron beams. An electron’s wavelength can be as small as a tenth of an angstrom. There have been developed electron microscopes with a resolution of 0.6 Å. An electron microscope can be used to determine the location of atoms and molecules in a substance.

The IMPERIAL SYSTEM was established by Britishers to measure a system of units. It was once used for measures in a variety of areas. The following are some of the most regularly used units in this system:

1. Nautical Mile
2. Mile
3. Furlong
4. Yards
5. Rod
6. Fathom
7. Feet
8. Inches

Unit Conversion Table for the Imperial System of units of Length

To measure length, we also have metric units. The kilometre, hectometre, decametre, metre, decimetre, centimetre, and millimetre are examples of these units. These units have a unique relationship. The base unit among these is the metre. The following table shows the relationship between each other unit and the base unit (metres):

Scientific Units of Length

1. Astronomical Unit: Astronomical units are used to measure the average distance between the Earth and the Sun. It is used everywhere around the Solar System to determine orbits and trajectories.

1 AU = 149,597,871 km 

1. Light Year: In one average solar year, the distance travelled by light is measured in light-years. In astronomy, it is used to measure extremely vast distances.

1 light-year = 9,461,000,000,000 km 

1. Parsec: A parsec is an astronomical unit of measurement that equates the distance between the earth and a one-second parallax-angle astronomical object.

1 parsec = 30,857,000,000,000 km  

Ranges of Length

We come across a wide variety of sizes of objects on a regular basis. They can range in size from 10-14 m of microscopic particles to 1026 m of the universe’s size. For small lengths, specific length units are required.

• 1 fermi = 1 f =10-15 m  
• 1 angstrom = 1Å= 10-10 m 
• 1 astronomical unit = 1 AU= 1.496 ×10 11 m  
• 1 light-year = 1ly= 9.46 × 1011  m  
• 1 parsec= 3.08 × 1016 m 

Conclusion

The measurement of something from one end to the other is called length. The CGS system stands for centimetre, gramme, and second. The FPS system stands for “foot, pound, and second.” The MKS system is made up of three units: metre, kilogramme, and second. The SI unit for length is the metre. m is the abbreviation for it. Astronomical units are used to measure the average distance between the Earth and the Sun. 1 AU equals 149,597,871 kilometres. In one average solar year, the distance travelled by light is measured in light-years. 9461,000,000,000 kilometres = 1 light-year A parsec is a measuring unit used in astronomy. 30.857,000,000,000 km = 1 parsec.