When white light is passed through prism, it splits into band of seven colors called spectrum.
VIBGYOR (V) = Shortest wavelength 400nm; R = Longest wavelength 450 nm
Continuous spectrum
When white light is analyzed by passing through prism, it splits into seven colors. These colors are so continuous that each of them merges into the next. Hence, this spectrum known as continuous spectrum.
Emission Spectrum
The spectrum of radiation emitted by a substance that has absorbed energy is called an emission spectrum.
It is noticed when radiations emitted from source are passed through a prism & received on photographic plate.
Emission spectrum is produced by supplying energy to a sample by heating it or irradiating it and the wavelength (or frequency) of the radiation emitted, as the
sample gives up the absorbed energy, is recorded.
Absorption Spectrum
Absorption spectrum is the spectrum obtained when radiation is passed through a sample of material. The sample absorbs radiation of certain wavelengths. The wavelengths which are absorbed are missing and come as dark lines.
An absorption spectrum is like the photographic negative of an emission spectrum
Spectroscopy
The study of emission or absorption spectra is referred as spectroscopy
Line Spectrum
The spectrum of the visible light, is continuous as all wavelengths (red to violet) of the visible light are represented in the spectra. The emission spectra of atoms in the gas phase, on the other hand, do not show a continuous spread of wavelength from red to violet, rather they emit light only at specific wavelengths with dark spaces between them. Such spectra are called line spectra or atomic spectra
Every element has a unique line emission spectrum. The characteristic lines in atomic spectra can be used in chemical analysis to identify unknown atoms in the same way as fingerprints are used to identify people
Example
Both of the Emission And absorption spectrum is described in below figure
Emission Spectra
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 as 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 a time, the collection of atoms contains all possible excited states. The light emitted as these atoms fall to lower energy states is responsible for the spectrum
Absorption Spectra
When white light is passed through unexcited atomic hydrogen and then through a slit and prism, the transmitted light is lacking in intensity at the same wavelengths as are emitted spectra The recorded absorption spectrum is also a line spectrum and the photographic negative of the emission spectrum.
