Name the three types of spectra and explain briefly the causes of these spectra
1. Continuous spectra: Continuous spectra are produced when a solid, liquid, or dense gas emits light at all wavelengths. The atoms and molecules within the substance are at a range of energy levels, leading to a continuous distribution of emitted photons across a broad range of wavelengths.
2. Emission spectra: Emission spectra are produced when a low-density gas or plasma emits light at specific wavelengths. This occurs when electrons in the atoms or molecules are excited to higher energy levels and then return to lower energy levels, releasing photons of specific energies in the form of discrete spectral lines.
3. Absorption spectra: Absorption spectra are produced when light from a continuous source passes through a cool, low-density gas or a mixture of gas and solid particles. The atoms and molecules in the gas absorb specific wavelengths of light, which are missing in the transmitted spectrum. This creates dark absorption lines superimposed on the continuous spectrum, indicating the presence of certain elements or molecules in the intervening medium.