The diagram illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see an absorption spectrum?

Question

Quizplus · Accepted Answer

An absorption spectrum is produced when a cold gas absorbs certain wavelengths of light from a hotter source behind it. In this diagram, we can see that there is a gas cloud between the light source and the observer along line of sight 3. Therefore, an observer would see an absorption spectrum along line of sight 3. There is no gas cloud along line of sight 1 or 2, so an observer would not see an absorption spectrum along those lines of sight. Therefore, the correct answer is Choice C, line of sight 3.

The Diagram Illustrates a Light Source, a Gas Cloud, and Three