Question
Calculate the velocity of a star moving relative to the earth if you observe a wavelength of 91.0 nm for ionized hydrogen capturing an electron directly into the lowest orbital (that is, a $n_i = \infty$ to $n_f = 1$, or a Lyman series transition).
$-5.19 \times 10^{5}\textrm{ m/s}$
This is towards Earth.
Solution Video