Measurement of length

Introduction:

Length is the measurement of distance, and the size of a length is derived through various methods. This article will get information about such length concepts, Standard Unit (SI) of measuring the length, and other related terms. 

To learn about exact details of any object, distance, or other related things, measurement is required. Size of any physical quantity involves the long process of comparing a base, unanimously chosen, internationally accepted as a standard unit reference. The size of a physical amount is represented as a number accompanied by a variable known as a unit. In simple words, size is when the physical objects or parameters like force, distance, heat, displacement, etc., are converted into easily readable numeric terms. 

Various units are used to represent a measurement of a physical quantity. We may have significant numeral representations, but we need a limited unit to represent the large physical quantities, as they are interrelated. There are fundamental or base units that describe the base quantities, and the other quantities are represented as the derived units. The combination of these units is later known as the system of units. 

What is the International System of Units? 

There were different units for different countries’ measurement systems in earlier times. Examples of such measurements are the CGS, the FPS or the British system, and the MKS system. There were different lengths, mass, and time bases for these systems. For instance, CGS had a centimetre base, gram, and seconds, respectively. The FPS had a base unit of the foot, pound, and second, respectively. And the MKS system had the base units of meter, kilogram, and second, respectively. 

The system of units accepted internationally for measurement is Système Internationale d’Unites (French for International System of Units), also known as SI. It was generally accepted and developed by the Bureau International des Poids et measures (The International Bureau of Weights and Measures, BIPM) in 1971. It conveyed the measurement by the scheme of symbols, units, and abbreviations used worldwide. There is a standard SI unit for all, and it was updated in 2018 recently. 

What is Length? 

Length is the term used to identify the size of an object or distance. Length can be defined as measuring an object or a distance of how long it is from one point to another. Identifying the size or distance of an object from one point to another is the best way. We must understand the Standard Unit of measuring length. 

What are different units of length? 

According to the new international units, the standard unit of length is based on the metric system meter (m). So, the SI unit of length is meter, abbreviated as m. As per the length which is required to be measured, we can convert a meter into various units like millilitres (mm), kilometre (km), centimetre (cm). This centimetre and millimetre measure the small lengths like a pencil. At the same time, kilometres are used to measure the long lengths, like the distance between two roads, buildings, or destinations. We can use these units of measurement to define the length of any object. For instance, the distance between two table points is 2 m or 200 cm. Now, let’s understand the types of measurements of length. 

What are different types of measurement of length? 

There are different types of measurement of length, which is globally accepted. The methods include direct, indirect, or other forms. 

The Direct Method of measurement: 

 This type of measurement is in which the quantity is directly derived by using a measuring tool. The quantity result is expressed in terms of numbers. It is commonly used to measure physical quantities like length, pressure, temperature, etc. For instance, the physical balance is calculated as the weight of the matter. It describes the exact measurement as you are looking at it. Some examples are weight; distance is directly measured. 

Indirect Method of Measurement: 

Usually, the direct method gives inaccurate results most of the time; therefore, people tend to use the Indirect Method. In this method, the physical parameters are measured using a direct method, and then the quantity is determined by the numerical value. For instance, the length, breadth, and height is calculated using the Direct Method, and the relation of the direct method observes the weight. The indirect method, in short, describes the measuring of one item by the measurement of another item. If we understand it in simple terms, if you want to find the wind speed, you cannot directly measure it, but if you make a windmill and calculate how much power the windmill is generating, you can understand the speed of the wind. 

Parallax method:

The simple measurement of a meter, kilometres, etc., can be done by the direct method. If the range is not within our limits, we use the Indirect Method. But if there is a very long length that is entirely beyond our reach, then it cannot be measured by using a meter scale or any other method. For instance, the distance between the earth and the sun cannot be measured with a scale. So, to gain the measurement of such lengths, we have a parallax method. It is also known as the method of triangulation. 

It observes how there is displacement or change in the apparent position of an object when viewed from two different points. For instance, take a pencil and place it in front of you against a specific position on the wall. Now look at the pencil from your left eye (by closing the right eye) and again see it from your right eye (by closing the left eye). You would see the difference that if you see a similar object from two different points, the positions seem to change. It is known as the parallax method. The distance between two points is known as the basis. This example has a basis of eyes.