Cookies

We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Department of Physics

Constants and SI Units

Table 1: SI Base Units
Dimension Name Symbol
Length metre m
Mass kilogram kg
Time second s
Electric Current ampere A
Thermodynamic Temperature kelvin K
Amount of Substance mole mol
Luminous Intensity candela cd
Table 2: SI Derived Units
Dimension Name Symbol
Area square metre m2
Volume cubic metre m3
Speed / Velocity metre per second m s-1
Acceleration metre per second squared m s-2
Wave Number reciprocal metre m-1
Density / Mass Density kilogram per cubic metre kg m-3
Specific Volume cubic metre per kilogram m3kg-1
Current Density ampere per square metre A m-2
Magnetic Field Strength ampere per metre A m-1
Concentration mole per cubic metre mol m-3
Luminance candela per square metre cd m-2
Table 3: SI Derived Units With Special Names
Dimension Name Symbol Standard Units Base Units
Frequency hertz Hz s-1
Force newton N kg m s-2
Pressure / Stress pascal Pa N m-2 kg m-1 s-2
Energy / Work / Quantity of Heat joule J N m kg m2 s-2
Power watt W J s-1 kg m2 s-3
Electric Charge coulomb C A s
Voltage volt V W A-1 kg m2 s-3 A-1
Capacitance farad F C V-1 kg-1 m-2 s4 A2
Inductance henry H A-2 kg m2 s-2
Electric Resistance ohm Ω V A-1 kg m2 s-3 A-2
Celsius Temperature degree celsius °C K
Activity of a Radionuclide becquerel Bq s-1
Dynamic Viscosity pascal second Pa s kg m-1 s-1
Moment of Force newton meter N m kg m2 s-2
Heat Capacity / Entropy joule per kelvin J K-1 kg m 2 s-2 K-1
Specific Heat Capacity / Specific Entropy joule per kilogram kelvin J kg-1 K-1 m2 s-2 K-1
Specific Energy joule per kilogram J kg-1 m2 s-2
Thermal Conductivity watt per metre kelvin W m-1 K-1 kg m s-3 K-1
Energy Density joule per cubic metre J m-3 kg m-1 s-2
Electric Field Strength volt per metre V m-1 kg m s-3 A-1
Table 4: A selection of physical constants from CODATA 2006
Name Symbol Value
acceleration due to gravity (exact) g 9.806 65 ms2
unified atomic mass unit u 1.660 538 782(83) x 10-27 kg
Avogadro constant NA 6.022 141 79(30) x 1023 mol-1
Bohr magneton μB 9.274 009 15(23) x 10-24 J T-1
Bohr radius ao 5.291 772 0859(36) x 10-11 m
Boltzmann constant k 1.380 650 4(24) x 10-23 J K-1
electron charge magnitude e 1.602 176 487(40) x 10-19 C
electron mass me 9.109 382 15(45) x 10-31 kg
fine structure constant α 7.297 352 5376(50) x 10-3
inverse fine structure constant 1/α 137.035 999 679(94)
gravitational constant G 6.674 28(67) x 10-11 m3 kg-1 s-2
nuclear magneton μN 5.050 783 24(13)x 10-27 J T-1
permeability of free space μ0 4 π x 10-7 N A-2
permittivity of free space e0 8.854 187 817... x 10-12 F m-1
pi π 3.141 592 653...
Planck constant h 6.626 068 96(33) x 10-34 J s
proton (1H) mass mp 1.672 621 637(83) x 10-27 kg
speed of light in vacuum (exact) c 299 792 458 ms-1
Stefan-Boltzmann constant σ 5.670 400(40) x 10-8 W m-2 K-4