Which spectrum shows dark lines where a cooler gas absorbs specific wavelengths from a continuous source?

Which spectrum shows dark lines where a cooler gas absorbs specific wavelengths from a continuous source?

• A. Emission
• B. Diffraction
• C. Continuous
• D. Absorption

Answer: (D)

Absorption spectrum shows dark lines where cooler gas absorbs specific wavelengths from a continuous source. When light from a hot, continuous source passes through a cooler gas, electrons in the gas absorb photons at energies corresponding to the gaps between their allowed energy levels. Those particular wavelengths are removed from the beam, creating dark lines superimposed on the otherwise smooth rainbow. This contrast—dark absorption lines on a continuous spectrum—is what defines the absorption spectrum. (In comparison, an emission spectrum would have bright lines at specific wavelengths, a continuous spectrum has no dark lines, and diffraction relates to how light is spread but isn’t itself the type of spectrum here.)

Absorption spectrum shows dark lines where cooler gas absorbs specific wavelengths from a continuous source. When light from a hot, continuous source passes through a cooler gas, electrons in the gas absorb photons at energies corresponding to the gaps between their allowed energy levels. Those particular wavelengths are removed from the beam, creating dark lines superimposed on the otherwise smooth rainbow. This contrast—dark absorption lines on a continuous spectrum—is what defines the absorption spectrum. (In comparison, an emission spectrum would have bright lines at specific wavelengths, a continuous spectrum has no dark lines, and diffraction relates to how light is spread but isn’t itself the type of spectrum here.)