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Sunday 7 July 2013

Measurement And System OF Unit

                           All Physical quantities are measured with standard quantity called as unit.


UNIT :- The standard quantity which is used for for the measurement of physical quantities is called unit.

Magnitude :- The number in which size or length of physical quantity is called magnitude .
Example : 10metre ( Here 10 is magnitude and metre is unit)

System oF UNITS :- There are Four system of measurement .

(1) C.G.S System (2) F.P.S System (3) M.K.S System (4)S.I Units

(1) C.G.S System :- Centimeter , gram , and second system . In this system centimeter gram and second are basic units

MCQ:- Length mass and time are basic quantities .
MCQ:- Force is derived quantity in C.G.S, M.K.S And S.I Units .


(2) F.P.S System : - Foot  Pound second System . In this system length force and time are basic qauntities .

MCQ:- Mass is derived quantity in F.P.S System .


(3) M.K.S System :- Metre Kilogram second system . In this system  lenght mass and time are fundamental quantities .



(4) S.I UNIT :- This system was approved by general conference on weights and measures in the Zurich City near Paris in France in 1960 A.D .

=> In this system there are seven basic units two suplementry units .



Lenght                                                    Unit                                                        Symbol

Length = L                                              Meter                                                      m
Mass = M                                               Kilogram                                                 kg
Time = t                                                  second                                                     s
Electric Current = I                                 Ampere                                                    A
Temperature = T                                     Kelvin                                                      K
Amount of Substance = n                        Mole                                                        mol
Luminous Intensity = Iv                           Candela                                                    cd


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