Fundamental And Derived Units

Fundamental And Derived Units:

The measurable property of a material body is called physical quantity.
For example Length, mass, area, density, force, volume etc.

The physical quantities are classified into two types.


i) fundamental physical quantities, ii) derived physical quantities.

a. Fundamental physical quantities
The physical quantities which do not depend on other physical quantities for their measurements are
called fundamental physical quantities or basic physical quantities.

Fundamental units or basic units

The unit of fundamental physical quantity is called fundamental units. These are not derived from any other
units and cannot be further resolved into other more simpler units. The number of basic units are only seven.



Sr. No.

Basic Physical Quantity

Name of the SI unit

Symbol

1

Length

meter

m

2

Mass

Kilogram

kg

3

Time

second

S or sec

4

Temperature

kelvin

K

5

Electric Current

ampere

A

6

Luminous intensity

candela

Cd

7

Amount of Substance

mole

mol



Supplementary Physical Quantity:

Plane angle and solid angle are called supplementary physical Quantity

Supplementary Units

Supplementary Physical Quantity

Name Of SI Unit

Symbol

Plane Angle

radian

rad

Solid angle

Steradian

sr



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