We are measuring the spectra of two hydrogen gas clouds. The laboratory frame wavelength of one hydrogen line is 656.2 nm. Cloud A's emission line wavelength is 660.1 nm and Cloud B's emission line wavelength is 670.1 nm. What can we conclude about these clouds?

Question

Quizplus · Accepted Answer

The laboratory frame wavelength of the hydrogen line is smaller than both Cloud A's and Cloud B's emission line wavelengths. This means both clouds are emitting light with longer wavelengths (redshifted) than the laboratory frame, indicating they are both receding from us. Additionally, Cloud B's emission line has a longer wavelength than Cloud A's, indicating that Cloud B is receding faster than Cloud A. Therefore, the correct answer is D.

We Are Measuring the Spectra of Two Hydrogen Gas Clouds