The Physics
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Opus in profectus

Physical Constants

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Physical constants Source: NIST, exception *NASA
symbol name value unit
c  
speed of light in a vacuum
 
299,792,458   m/s
G  
gravitational constant
 
6.67408 × 10−11 N m2/kg2
h  
planck constant
 
6.626070040
 4.135667662
× 10−34
× 10−15
J s
eV s
hc  

 
1.98644582
1239.84197
× 10−25
 
J m
eV nm
h/2π
reduced planck's constant
dirac's constant
1.054571800
 6.582119514
× 10−34
× 10−16
J s
eV s
ε0 electric constant
permitivitty of free space
vacuum permitivitty
8.854187817 × 10−12 C2/N m2
μ0 magnetic constant
permeability of free space
vacuum permeability
× 10−7 T m/A
e  
elementary charge
 
1.6021766208 × 10−19 C
me  
electron mass
 
9.10938356
0.5109989461
0.000548579909070
× 10−31

 
kg
MeV
u
mp  
proton mass
 
1.672621898
938.2720813
1.007276466879
× 10−27

 
kg
MeV
u
mn  
neutron mass
 
1.674927471
939.5654133
1.00866491588
× 10−27

 
kg
MeV
u
mu  
atomic mass constant
 
1.660539040
931.4940954
1
× 10−27

 
kg
MeV
u
NA  
avogadro's constant
 
6.022140857 × 1023 1/mol
k  
boltzmann's constant
 
1.38064852 × 10−23 J/K
R  
gas constant
 
8.3144598   J/mol K
σ  
stefan-boltzmann constant
 
5.670367 × 10−8 W/m2K4
b  
wien displacement constant
 
2.8977729
58.789238
  mm/K
GHz/K
g  
standard gravity
 
9.80665   m/s2
atm  
standard atmosphere
 
101,325   Pa
H0
hubble constant*
 
69.3
2.25
 
× 10−18
km/s/Mpc
s−1