Page 4 - Materials Science and Engineering An Introduction

Values of Selected Physical Constants
Quantity Symbol SI Units cgs Units
Avogadro’s number N A 6.022 10 23 6.022 10 23
molecules/mol molecules/mol
Boltzmann’s constant k 1.38 10 23 J/atom K # 1.38 10 16 erg/atom K #
8.62 10 5 eV/atom K #
24 #
Bohr magneton m B 9.27 10 A m 2 9.27 10 21 erg/gauss a
Electron charge e 1.602 10 19 C 4.8 10 10 statcoul b
Electron mass — 9.11 10 31 kg 9.11 10 28 g
Gas constant R 8.31 J/mol K # 1.987 cal/mol K #
Permeability of a vacuum m 0 1.257 10 6 henry/m unity a
Permittivity of a vacuum 0 8.85 10 12 farad/m unity b
34 #
Planck’s constant h 6.63 10 J s 6.63 10 27 erg s #
4.13 10 15 eV s #
8
10
Velocity of light in a vacuum c 3 10 m/s 3 10 cm/s
a
In cgs-emu units.
b
In cgs-esu units.

Unit Abbreviations
A ampere in. inch N newton
Å angstrom J joule nm nanometer
Btu British thermal unit K degrees Kelvin P poise
C Coulomb kg kilogram Pa Pascal
C degrees Celsius lb f pound force s second
cal calorie (gram) lb m pound mass T temperature
cm centimeter m meter m micrometer
eV electron volt Mg megagram (micron)
F degrees Fahrenheit mm millimeter W watt
ft foot mol mole psi pounds per square
g gram MPa megapascal inch

SI Multiple and Submultiple Prefixes

Factor by Which
Multiplied Prefix Symbol
10 9 giga G
10 6 mega M
10 3 kilo k
10 2 centi a c
10 3 milli m
10 6 micro
10 9 nano n
10 12 pico p
a
Avoided when possible.