Final answer:
To produce an absorption spectrum, you need a hot, dense object, such as a lightbulb, and a cooler thin gas through which the light from the object can pass. The gas absorbs certain wavelengths of light, leading to dark lines in the continuous spectrum. a) a hot, dense object and a cooler thin gas
Step-by-step explanation:
To produce an absorption spectrum, certain conditions must be met involving specific characteristics of light and matter. An absorption spectrum is a series or pattern of dark lines that are superimposed on a continuous spectrum. This particular type of spectrum is created when white light from a hot, dense object such as an incandescent lightbulb passes through a cooler, thinner gas. The gas absorbs specific wavelengths of light, which correspond to the electronic transitions of the gas's atoms, thus creating the observed series of dark lines within the continuous spectrum. The exact components required are a hot, dense object (like a lightbulb or a star) and a cooler thin gas. This setup allows us to see a continuous spectrum of light with superimposed dark absorption lines where the cooler gas has absorbed certain wavelengths. When a hot thin gas itself is excited and observed with no continuous background, it emits specific wavelengths of light creating an emission spectrum. If we look only at this cloud of excited gas atoms, we see that these atoms give off an emission line spectrum. Thus, for an absorption spectrum to be visible, the correct answer to the question is: a) a hot, dense object and a cooler thin gas.