Quantity

Symbol

Value

SI Units

Cgs Units

Velocity of light

c

2.9979250

10⁸ m/sec

10¹⁰ cm/sec

Free space permittivity

e_o

8.8541

10^-12 F / m

10^-14 F / cm

Free space permeability

m_o

1.2566

10^-6 H / m

10^-8 H / cm

Fine-structure constant

a

7.297351

10^-3

10^-3

Electron charge

e

1.6021917

10^-19 C

10^-20 emu

Planck's constant

h

6.626196

10^-34 J-sec

10^-27 erg-sec

Avogadro's number

N

6.022169

10²⁶ kmole^-1

10²³ mole^-1

Atomic mass unit

amu

1.660531

10^-27 kg

10^-24 gm

Electron rest mass

m_e

9.109558

10^-31 kg

10^-28 gm

Proton rest mass

M_p

1.672614

10^-27 kg

10^-24 gm

Neutron rest mass

M_n

1.674920

10^-27 kg

10^-24 gm

Proton / electron mass ratio

M_p / m_e

1836.109

Electron charge / mass ratio

e / m_e

1.7588028

10¹¹ C / kg

10⁷ emu / gm

Faraday constant

F

9.648670

10⁷ C / kmole

10³ emu / mole

Rydberg constant

R_¥

1.09737312

10⁷ m^-1

10⁵ cm^-1

Boltzman constant

K

1.3807

10^-23 J / K

10^-16 erg / K

Stefan-Boltzman constant

s

5.671

10^-8 W / m² K⁴

10^-5 W / cm² K⁴

Gravitational constant

g

9.8067

kg m / s²

10⁵ gm cm / s²

Loschmidt constant

n_o

2.6868

10²⁵ m^-3

10¹⁹ cm^-3

Bohr radius

a_o

5.2917715

10^-11 m

10^-9 cm

Classical electron radius

r_o

2.817939

10^-15 m

10^-13 cm

Standard atmosphere

atm

1.0132 x 10⁵ Pa

1.0125 x 10⁶ erg / cm³