Question

An absorbtion spectrum is like photographic negative of an emission spectrum. Give reasons.

Answer 1

A material's absorption spectrum shows the fraction of incident electromagnetic radiation absorbed by the material over a range of frequencies. An absorption spectrum is, in a sense, the inverse of an emission spectrum. Every chemical element has absorption lines at several particular wavelengths corresponding to the differences between the energy levels of its atomic orbitals. For example, an object that absorbs blue, green and yellow light will appear red when viewed under white light. Absorption spectra can, therefore, be used to identify elements present in a gas or liquid. This method is used for checking the presence of elements in stars and other gaseous objects which cannot be measured directly.