Symbol

Represents

h

Planck constant

$\hslash$

reduced Planck constant

c

speed of light

v

velocity of the electron

Z

atomic number

$R_{\infty }$

Rydberg constant

$n_1$

the principal quantum number of an energy level

$n_2$

the principal quantum number of an energy level for the atomic electron transition

${ϵ}_0$

vacuum permittivity

$\alpha$

Fine structure constant

e

elementary charge

$\lambda$

Photon wavelength

${\lambda }_e$

Compton wavelength electron

${\overline{\lambda }}_e$

Reduced Compton wavelength electron

$m_e$

rest mass of electron

$m_P$

rest mass of proton

p

momentum

E

energy

$E_k$

kinetic energy