These two results then allow one to express the sum of the kinetic(1/2 me v) and Coulomb potential (-Ze"/r)energies E=-1/2m。Z2e(nh/2 Just as in the Bragg diffraction result, which specified at what angles special high intensities occurred in the scattering, there are many stable Bohr orbits, each labeled by a value of the integer n. Those with small n have small radi, high velocities and more negative total energies(n b, the reference zero of energy corresponds to the electron at r oo, and withv=0). So, it is the result that only certain orbits are allowed" that causes only certain energies to occur and thus only certain energies to be observed in the emitted photons It turned out that the bohr formula for the energy levels (labeled by n)of an electron moving about a nucleus could be used to explain the discrete line emission spectra of all one-electron atoms and ions(i.e, H, He, Li, etc. )to very high precision In such an interpretation of the experimental data, one claims that a photon of energy hv=R(l/m2-1/n2) is emitted when the atom or ion undergoes a transition from an orbit having quantum number n, to a lower-energy orbit having n here the symbol r is used to denote the following collection of factors9 These two results then allow one to express the sum of the kinetic (1/2 me v 2 ) and Coulomb potential (-Ze2 /r) energies as E = -1/2 me Z2 e4 /(nh/2p) 2 . Just as in the Bragg diffraction result, which specified at what angles special high intensities occurred in the scattering, there are many stable Bohr orbits, each labeled by a value of the integer n. Those with small n have small radii, high velocities and more negative total energies (n.b., the reference zero of energy corresponds to the electron at r = ¥ , and with v = 0). So, it is the result that only certain orbits are “allowed” that causes only certain energies to occur and thus only certain energies to be observed in the emitted photons. It turned out that the Bohr formula for the energy levels (labeled by n) of an electron moving about a nucleus could be used to explain the discrete line emission spectra of all one-electron atoms and ions (i.e., H, He+ , Li+2, etc.) to very high precision. In such an interpretation of the experimental data, one claims that a photon of energy hn = R (1/nf 2 – 1/ni 2 ) is emitted when the atom or ion undergoes a transition from an orbit having quantum number ni to a lower-energy orbit having nf . Here the symbol R is used to denote the following collection of factors: