Base Quantities | Arizona State University

University:
Arizona State University
Course:
PHYS 102 | Introductory Physics I
Academic year:

2024
Views:

129

Pages:

3
Author:

Mohammed N.

Base Quantities A physical quantity is a property of a phenomenon, an objects or a substance that can be quantified. The measure can be expressed with a number and a unit of measurement. The International System of Units of Measurement classifies physical quantities into base quantities and derived quantities. The dimension of a physical quantity does not include magnitude or units. The derived quantities instead are defined from the base quantities. The Base Physical Quantities are: - Length: meter m The meter is defined as the length of the path travelled by light in a vacuum in 1/299792458 of a second. - Mass: kilogram Kg The kilogram is defined by the mass of the platinum alloy cylinder kept in the museum of measurements in Sèvres (France). - Time: second S A second is defined as the time it takes a Cesium atom to complete 9192631770 periods of radiation corresponding to the transition between two hyperfine levels, from (F=4, MF=0) to (F=3, MF=0). - Thermodynamic temperature: Kelvin K the kelvin was defined to be the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. - Electric Current: Ampere A The formal definition of an ampere is the constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2 × 10^-7 Newton per metre of length. - Amount of substance: mole mol The mole is the amount of substance of a system that contains as many elementary entities as there are atoms in 12 grams of Carbon. - Luminous magnitude : candela cd It is defined as the luminous magnitude in a given direction of a source that emits monochromatic radiation of frequency 540*10^12 Hertz and has a radiant magnitude in that same direction of 1/683 W/sr.