Explain emission and absorption spectra.

(N/A) Absorption spectra: When electromagnetic radiation interacts with an object,it can be absorbed by atoms,molecules,or ions,causing them to transition from a lower energy state $E_{1}$ to a higher energy state $E_{2}$. The energy absorbed is given by $\Delta E = E_{2} - E_{1} = h\nu$. This process results in an absorption spectrum,which appears as dark lines in a continuous spectrum.
Emission spectra: Atoms or molecules in an excited state $E_{2}$ are unstable and tend to return to a lower energy state $E_{1}$ by releasing energy in the form of electromagnetic radiation. The energy emitted is given by $\Delta E = E_{2} - E_{1} = h\nu$. This process results in an emission spectrum,which appears as bright lines on a dark background.
Spectroscopy: The study of emission or absorption spectra is referred to as spectroscopy. In the gaseous phase,these spectra are not continuous but consist of discrete lines.