atomic emission the light emitted by a sample of excited hydrogen atoms(or any other element) can be passed through a prism and separated into certain discrete wavelengths. thus, an emission spectrum, which is a photographic recording of the separated wavelengths, is called a line spectrum. any sample of reasonable size contains an enormous number of atoms. although a single atom can be in only one excited state at time, the collection of atoms contains all possible exited stat. the light emitted as these atoms fall to lower energy states is responsible for the spectrum. (b) atomic absorption. when white light is passed though unexcited hydrogen and then though a slit and a prism, the transmitted light is lacking in intensity at the same wavelengths as are emitted in part (a). The recorded absorption spectrum is a line spectrum and the photographic negative of the emission spectrum.