# Si Units list ## What is unit?

The term unit indicates the amount or magnitude of any quantity which is measurable. Different units are used to indicate different measurements of particular kind of quantities.

## What is unit in Physics?

In physics, there are a lot of physical quantities which are measured to perform an experiment and a lot of physical quantities which form the basis of mathematical equations which govern laws of physics such as length, mass and many more. In order to measure such physical quantities, Appropriate units are made to measure them accurately.

## What is SI unit?

The term SI stands for International system of units. This is the standard system of measurements of units which is used by all the countries to measure any physical quantities. It was made to resolve the issue of different units used by different countries to measure a particular physical quantity.

The SI unit system consists of seven fundamental physical quantities units and these are fundamental because any other physical quantity in physics can be derived from these quantities relations. Any Physical quantity unit which is derived from fundamental physical quantities is known as Derived units.

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## Fundamental Physical Quantities:

In physics, there are seven fundamental physical quantities which form the basis for deriving any other physical quantities. These seven fundamental physical quantities are listed as:

1. Length
2. Time
3. Mass
4. Electric current
5. Luminous intensity
6. Amount of substance
7. Temperature.

Definition, Symbols and SI units List of Fundamental physical Quantities:

Below is the SI unit list chart indicating their definition, symbols along with their SI unit.

 Quantity Name Definition SI Unit Symbol Length Length is defined as the distance between two points of any object. meter m Time Time is the sequence of events that occurred in nature. second s Mass Mass is defined as the total amount of matter present in a body. Kilogram s Electric current Electric current is defined as the flow of electric charges inside a material. Ampere A Luminous Intensity Luminous Intensity is the total amount of visible light emitted in a unit of time per unit of solid angle. Candela Cd Amount of Substance The measurement of the number of atoms or molecules inside a material is called Amount of substance. Mole mol Temperature The measurement of intensity of heat inside a body is called temperature. Kelvin K

## Define Derived Units.

In physics, other than these seven fundamental physical quantities, any physical quantity can be derived from the relationship between these fundamental physical quantities and hence, these quantities are called derived quantities and units of such quantities are known as derived units.

Some of the most common and used derived units are listed below with their definition, SI units and their symbols.

 Quantity Name Definition SI unit symbol Area It’s the amount of space covered by an object in two dimensional plane meter square m2 Volume It’s the amount of space covered by an object in three dimensional space. meter cube m3 Velocity Velocity is the ratio of distance covered by a body over time. meter per second ms-1 Acceleration Acceleration is the ratio of velocity of a body over time. meter per second square ms-2 Force The product between mass of a body and the acceleration produced in it is called Force. Newton N Frequency The number of oscillations of a body in one second is called frequency. Hertz Hz Work The product of force applied on a body and the displacement covered by it is known as work done. Joule J Pressure Pressure is the ratio between force acting on a body to the area to which force is applied. Pascal Pa Power Power is defined as the ratio between work done by a body over a given period of time. Watts W Density Density is defined as the ratio between mass and volume of a body. Kilogram per meter cube Kgm-3

These are some derived units and there are more, in brief other than those seven fundamental physical quantities every quantity which is measurable in physics will be derived from those seven fundamental physical quantities and their SI unit name and symbol is after the scientist who discovered a particular kind of physical quantity. For example, It was. Isaac Newton who gave the idea of force so, SI unit of force or derived unit of force is called Newton, named after S. Isaac Newton.

Different units for measurement of most used fundamental physical quantities other than SI base units:

In physics, a single physical quantity can be measured in many different units with respect to their SI units due to their very large numerical values sometimes, some of most used Fundamental physical quantities can also be measured in different units are listed as”

Length:

Since, The SI unit of length is meter and its symbol is m. Along with this unit, following are most common used units for the measurement of length are given in unit table as:

 Name of unit Symbol Relation with SI unit of Length (m) Centimetre cm 1m=100cm Nanometre nm 1nm=10-9m millimetre mm 1mm=10-3m decimetre dm 1dm=0.1m Angstrom A° 1A°=10-10m Kilometre Km 1km=1000m Yard yd 1yd=0.914m Inch in 1in=0.0254 foot ft 1ft=0.305m

Time:

Since, The SI unit of time is second and its symbol is s. Along with this unit, following are most common used units for the measurement of time are given in unit table as:

 Name of Unit Symbol Relation with SI unit of Time (s) Minute min 1min=60s Hour hr 1hr=3600s Day Day 1day=24hr Year yr 1yr=365days

Mass:

Since, The SI unit of mass is Kilogram and its symbol is Kg. Along with this unit, following are most common used units for the measurement of mass are given in unit table as:

 Name of unit Symbol Relation with SI unit of Mass (Kg) Grams gm 1Kg=1000gm Decigram dgm 1dgm=0.1gm Centigram cgm 1cgm=0.01gm