The spectra of most stars are dark-line spectra because ________.
A)elements in the Sun's outer atmosphere emit radiation between these dark bands
B)elements in the Sun's outer atmosphere absorb in these dark-line bands,blocking the radiation in those bands
C)elements in the earth's atmosphere absorb in these dark-line bands,blocking out the frequencies in the dark bands
D)electrons decaying to a lower energy state emit a photon at a fixed energy,leaving dark bands between the emissions

Question

Quizplus · Accepted Answer

The dark lines in the spectra of stars are caused by elements in the star's outer atmosphere absorbing radiation at specific wavelengths, which creates gaps or "lines" in the overall spectrum. The gaps correspond to the specific elements that are absorbing the radiation, and the pattern of lines can be used to determine the chemical composition of the star. Therefore, option B is the correct choice. Option A is incorrect because elements in the Sun's outer atmosphere do not emit radiation between the dark bands; they absorb it. Option C is incorrect because the dark-line spectra are not caused by absorption in the Earth's atmosphere. Option D is incorrect because the electrons decaying to a lower energy state actually emit photons at specific wavelengths, which create bright lines in the spectrum, not dark ones.

The Spectra of Most Stars Are Dark-Line Spectra Because ________