SI Units List and Details PDF

PDF Name	SI Units List and Details
No. of Pages	7
PDF Size	0.02 MB
Language	English
PDF Category	General
Source / Credits	webpages.uidaho.edu
Uploaded By	Pradeep

SI Units List and Details - Summary

SI units form the base of the International System of Units. This modern metric system is used worldwide for measurements. Officially accepted in almost every country, SI units give you a uniform way to measure physical quantities.

Overview of SI Units: Basics You Should Know in 2025

The SI system includes seven basic units. Each stands for an important physical quantity. These are meter for length (m), kilogram for mass (kg), second for time (s), ampere for electric current (A), kelvin for temperature (K), mole for amount of substance (mol), and candela for light intensity (cd).

Quick Reference: Complete SI Units List and Symbols

Here’s a simple table showing the seven SI base units:

Sl. No.	Name of the Quantity	SI Unit	SI Unit Symbol
1.	Length (l)	Meter	m
2.	Mass (M)	Kilogram	kg
3.	Time (T)	Second	s
4.	Electric current (I)	Ampere	A
5.	Thermodynamic temperature (Θ)	Kelvin	K
6.	Amount of substance (N)	Mole	mol
7.	Luminous intensity (J)	Candela	cd

Detailed SI Base Units List – Definitions and Importance

There are 7 SI base units. Each unit has a clear definition based on fundamental constants. This makes them well-known and consistent everywhere.

Unit of length, meter (m): The meter is defined by fixing the speed of light in vacuum as a constant. It is measured in m.s^-1.
Unit of mass, kilogram (kg): The kilogram is defined by the fixed value of Planck’s constant, which is h = 6.62607015×10^-34 J⋅s. Its unit expression is kg.m².s^-1.
Unit of time, second (s): The second is defined by the frequency of a specific transition in Cesium-133 atoms. This frequency is exactly 9,192,631,770 hertz. It is expressed as s¹.
Unit of electric current, ampere (A): Ampere is based on the fixed value of the elementary electric charge, which is e = 1.602176634×10^-19 C.
Unit of thermodynamic temperature, Kelvin (K): Kelvin uses the fixed Boltzmann constant value k = 1.380649×10^-23 J⋅K^-1.
Unit of the amount of substance, mole (mol): Mole is defined by Avogadro’s constant N_A. One mole contains exactly 6.02214076×10²³ elementary entities. This number is also called Avogadro number.
Unit of luminous intensity, candela (cd): Candela is based on a fixed value of luminous efficacy of a monochromatic radiation of frequency 540×10¹² Hz, which is Kcd = 683 lm/W.

Knowing these base SI units helps you take accurate measurements in science, technology, and daily life in 2025. You can easily download the SI Units list PDF from the link available on this page.

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