During an observational survey of active galactic nuclei, astronomers measure the spectrum of a distant Seyfert galaxy. They detect the prominent Hβ\text{H}\betaHβ hydrogen emission line at an observed wavelength of 512 nm512\text{ nm}512 nm. In a stationary laboratory reference frame, this same emission line has a wavelength of 486 nm486\text{ nm}486 nm.
What is the recessional speed of this galaxy?
7.8×106 m s−17.8 \times 10^6\text{ m s}^{-1}7.8×106 m s−1
1.5×107 m s−11.5 \times 10^7\text{ m s}^{-1}1.5×107 m s−1
1.6×107 m s−11.6 \times 10^7\text{ m s}^{-1}1.6×107 m s−1
3.2×108 m s−13.2 \times 10^8\text{ m s}^{-1}3.2×108 m s−1
66 exam-style questions on OCR A A Level Physics Astrophysics and cosmology, covering Stars, Electromagnetic radiation from stars, and Cosmology. Each one has a worked solution and a mark scheme showing where the marks go.