Physics

Measurement

The process of Comparing the unknown physical quantity with know physical quantity

It consist of two parts

i) numerical value  Ii) physics units

Ex: 10 km

Quantity: quantity means size or amount of given quantity

Physical Quantitie:  which can be measured

Kinds of physical quantity

1. Fundamental physical quantity ii)Derived physical quantity iii) Supplementary physical quantity

Fundamental physical quantity

  The fundamental physical quantities are those which don’t depend up on other quantities and independent of each other.

1. Mass :The quantity of matter present in an object or body is called mass
2. Length: The extent from end to end of an object is called length.
3. Time: the interval between two events is referred as time
4. Amount of substance: the objects and materials are made up of small tiny particles called molecules or atoms. The number of molecules or atoms in a material is mole. It is a number which describes the amount of substance. 

• Luminous intensity : the  Luminous flux emitted through unit of solid angle is called Luminous intensity

Luminous flux: the total amount of light energy radiated from light source in all directions.

• Electric current : the rate of flow of charge through conductor
• Thermodynamic temperature: The degrees of coldness and hotness of body

Derived Physical quantity

The physical quantities which can be derived from fundamental quantities are called derived quantities.

Derived Physical quantities we experience in daily life are:

1. Area : The region enclosed by the boundary of an object is carled area.
2. Volume:The space occupied by an object is called its volume.
3. density : The mass present in a unit volume is called density.
4. Speed : the distance covered per unit time is called speed.
5. Velocity :The displacement produced in unit time is called velocity. It is specified with direction.
6. Acceleration: The rate of change of velocity is called acceleration. It is specified with direction. If a is decreasing its velocity it is said to be gaining retardation or deceleration.
7. Force: Which causes the change the state of object
8. work : The activity of displacing a body by applying force is referred as work.
9. Potential difference: work done per unit charge.
10. Power :the work done in unit time.
11. Pressure: the force per unit area
12. Energy : Ability to do work is called energy.

we experience the variety of energy in our world:

Heat energy : the form of energy which gives coldness and hotness of body

Light energy:the form of energy which gives visual sensation of human eye.

Electric energy: the form of energy produced by flowing charge is called Electric energy.

Supplementary Physical quantity:

SUPPLEMENTARY PHYSICAL QUANTITY	UNIT	SYMBOL
Plane angle	Radian	rad
Solid angle	steradian	sr

Plane angle                                   Solid angle

Plane angle: The union of two rays having same initial point is calied plane angle.

Solid angle: The angle present in a cone at the vertex is called solid angle.