Every one color match up to light of a certain wavelength produced by the atom when an electron marks a changeover among permissible orbitals. Each color signifies a jump of the electron with resultant emission of photons of certain energy conforming to the vertical colored stripes. The scientist can assess these energies by means of einstein equation for the energy of a photon which is E = h. v where v is the frequency of the emitted photon that can be assessed by means of the wavelength and h is a constant. Then it can recreate the jumps and accordingly figure out the orbitals and perhaps the map of the structure of the atom.
When beam of light passes through any material, electrons present in the atoms of the of the material absorbs photon and re-emits them. During this process electrons changes their orbit and falls back and emits light(photons) of a particular wavelength which determines colour of the spectrum and hence we can observe change in orbit of electrons and their current position. Thus determining structure of atom and also the nature of the material.
