) What is Sl units ? Explain its need.
Answers
Answer:
The International System of Units (abbreviated SI from systeme internationale , the French version of the name) is a scientific method of expressing the magnitudes or quantities of important natural phenomena. There are seven base units in the system, from which other units are derived
Answer:
SI unit is an international system of measurements that are used universally in technical and scientific research to avoid the confusion with the units. Having a standard unit system is important because it helps the entire world to understand the measurements in one set of unit system. Following is the table with base SI units:
There are 7 SI base units. The seven units along with their SI unit and symbol are given below:
Unit of length, meter (m): Meter is the SI unit of length and is defined by taking the fixed value of the speed of light in vacuum. It is expressed as m.s-1.
Unit of mass, kilogram (kg): Kilogram is the SI unit of mass and is defined by taking the fixed value of the Planck constant. It is expressed as kg.m2.s-1.
Unit of time, second (s): Second is the SI unit of time and is defined by taking the fixed value of Cesium frequency. It is expressed as s1.
Unit of electric current, ampere (A): Ampere is the SI unit of electric current and is defined by taking the fixed value of the elementary charge.
Unit of thermodynamic temperature, Kelvin (K): Kelvin is the SI unit of thermodynamic temperature and is defined by taking the fixed value of Boltzmann constant k = 1.380649×10-23.
Unit of the amount of substance, mole (mol): Mole is the SI unit of amount of substance and is defined by the fixed value of Avogadro constant NA. One mole contains 6.02214076×1023 elementary entities and is expressed as mol-1.
Unit of luminous intensity, candela (cd): Candela is the SI unit of luminous intensity and is defined by the fixed value of the luminous efficacy
