System of units and units in S.I system Flashcards
Define measurement
It is the process of comparison of the given physical quantity with the known standard quantity of the same nature.
Define Unit
Unit is a quantity of constant magnitude which is used. To measure magnitudes of other quantities of the same nature.
What are the parameters for measuring the magnitude of a physical quantity?
1) The unit
2) The magnitude
Fundamental quantities
Fundamental quantities are quantities which can neither be related o not be changed by any other physical quantity and are independent of any other quantity.
Derived quantities/units
Derive quantities/units are those quantities/units which depend on fundamental quantities or units or can be expressed in the form of fundamental quantities and units.
C .G.S System of units
C.G.S System of units or the french system of units is a system of units in which the units of length mass and times are centimeter, gram and seconds respectively.
F.P.S System
The F.P.S System of units is a system of units in which the units of length mass and time are foot, pound and second respectively.
M.K.S System.
The M.K.S System of units is a system of units in which the units of length, mass and time are metre, kilogram and second respectively.
Mole
It is defined as the amount of substance which contains as many constituent entities (protons, electrons, photons, molecules etc.) as the number of carbon atoms present in 12g of carbon
Avogadro’s Number
It is defined as the amount of substance which contains as many constituent entities (protons, electrons, photons, molecules etc.) as the number of carbon atoms present in 12g of carbon. This number is called Avogadro’s number and is equal to (6.022*10²³ mole-¹)
One metre
It is defined as the distance travelled by light in 1/299,792,458 th of a second.
One astronomical unit
Astronomical unit is the mean distance between the earth and the sun. It equal to 1.496*10¹¹ m
Light Year
A light year is the distance travelled by light in one year.
Kilogram
One kilogram is defined as the mass of a cylinder made of a platinum-iridium alloy, kept in the International Bureau of Weights and Measures in Sevres near Paris.
Atomic Mass unit
It is 1/12th the mass of a carbon-12 atom.
Solar Mass
One Solar Mass is equal to the mass of the sun which is around 2 * 10³⁰
One second
One second is the time interval of 9,192,631,770 vibrations of radiation corresponding to the transition between two ground state, unperturbed, levels of caesium-133 atom.
What is the period of of revolution of the earth around the sun called?
365.2422 days
1 year = _______s
3.1536 * 10⁷
What is a tropical year?
A tropical year is an year in which sun is taken as the reference point for positions. It is used as a year for the Georgian calendar.
