X-Ray Data Booklet

Section 5.1 PHYSICAL CONSTANTS

 

Table 5-1 was drawn from the recommendations of CODATA (the Committee on Data for Science and Technology). The full 1998 CODATA set of constants may be found at http://physics.nist.gov/cuu/Constants/index.html. A PDF version of this table is also available.

Table 5-1. Physical constants.



Quantity


Symbol, equation


Value

Uncert.
(ppb)

speed of light

c (see note *)

2.997 924 58108 m s1 (1010 cm s1)

exact

Planck constant

h

6.626 068 76(52)1034 J s (1027 erg s)

78

Planck constant, reduced

= h/2p

1.054 571 596(82)1034 J s = 6.582 118 89(26)1022 MeV s

78, 39

electron charge magnitude

e

4.803 204 20(19)1010 esu = 1.602 176 462(63)1019 C

39, 59

conversion constant

197.326 960 1(78) MeV fm (= eV nm)

39

electron mass

me

0.510 998 902(21) MeV/c2 = 9.109 381 88(72)1031 kg

40, 79

proton mass

mp

938.271 998(38) MeV/c2 = 1.672 621 58(13)1027 kg

40, 79

 

 

= 1.007 276 466 88(13) u = 1836.152 667 5(39) me

0.13, 2.1

deuteron mass

md

1875.612 762 (75) MeV/c2

40

unified atomic mass unit (u)

(mass 12C atom)/12 = (1 g)/(NA mol)

931.494 013(37) MeV/c2 = 1.660 538 73(13)1027 kg

40, 79

permittivity of free space

e0 = 1/(m0c2)

8.854 187 8171012 F m1

exact

permeability of free space

m0

4p107 N A2 = 12.566 370 614107 N A2

exact

fine-structure constant

a = e2/4pe0

1/137.035 999 76(50)

3.7

classical electron radius

re = e2/4pe0mec2

2.817 940 285(31)1015 m

11

Bohr radius (mnucleus = )

a0 = 4pe0/mee2 = rea2

0.529 177 208 3(19)1010 m (108 cm)

3.7

Rydberg energy

hcR = mee4/2(4pe0)2

=mec2a2/2

13.605 691 72(53) eV

39

Thomson cross section

sT = 8p/3

0.665 245 854(15) barn (1028 m2)

22

Bohr magneton

mB = e/2me

5.788 381 749(43)1011 MeV T1

7.3

nuclear magneton

mN = e/2mp

3.152 451 238(24)1014 MeV T1

7.6

electron cyclotron freq./field

/B = e/me

1.758 820 174(71)1011 rad s1 T1

40

proton cyclotron freq./field

/B = e/mp

9.578 834 08(38)107 rad s1 T1

40


 

Table 5-1. Physical constants(continued).



Quantity


Symbol, equation


Value

Uncert.
(ppb)

Avogadro constant

NA

6.022 141 99(47)1023 mol1

79

Boltzman constant

k

1.380 650 3(24)1023 J K1 = 8.617 342(15)105 eV K1

1700

molar volume, ideal gas at STP

NAk (273.15 K)/(101 325 Pa)

22.413 996(39)103 m3 mol1

1700

p = 3.141 592 653 589 793 238

e = 2.718 281 828 459 045 235

g = 0.577 215 664 901 532 861

The meter is the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second.

1 in. = 2.54 cm

1 newton = 105 dyne

1 eV/c2 = 1.782 6621033 g

1 coulomb = 2.997 924 58109 esu

1 = 108 cm

1 joule = 107 erg

hc/(1 eV) = 1.239 842 mm

1 tesla = 104 gauss

1 fm = 1013 cm

1 cal = 4.184 joule

1 eV/h = 2.417 9891014 Hz

1 atm = 1.013 25106 dyne/cm2

1 barn = 1024 cm2

1 eV = 1.602 176 51012 erg

1 eV/k = 11 604.5 K

0C = 273.15 K