PHYSICS & ELECTRONICS / MODERN PHYSICS / PAGE 27 OF 50
Bohr's Atom and Line Spectra
Why atoms emit light of only certain colours.
In Bohr's model of hydrogen, the electron can only occupy certain orbits with fixed energies. It does not radiate while in an orbit. When it jumps to a lower level it emits one photon whose energy equals the difference between the two levels.
Original diagram: bohr's atom and line spectra
This explained the sharp lines in the spectrum of hydrogen. The model has limits and was later replaced by quantum mechanics, but its energy levels remain a useful guide for hydrogen-like atoms.
- Energy levels are quantised, not continuous.
- Absorption lines appear at the same energies as emission lines.
- The ground state is the lowest level.
KEY IDEA
E_n = −13.6 eV / n²Browse all 50 physics and electronics pages | Back to the course index