Part of the emission spectrum for hydrogen in a laboratory shows two prominent lines at 434 nm434\text{ nm}434 nm and 486 nm486\text{ nm}486 nm. A spectrometer records spectra over the wavelength range of 410 nm410\text{ nm}410 nm to 460 nm460\text{ nm}460 nm.
An absorption spectrum of the same wavelength range is observed from Earth for light from a galaxy moving directly towards Earth with a velocity of 0.050c0.050c0.050c.
Which of the following describes the lines visible in this observed absorption spectrum within the spectrometer's range of 410 nm410\text{ nm}410 nm to 460 nm460\text{ nm}460 nm?
A single bright line at 412 nm412\text{ nm}412 nm on a dark background.
A single dark line at 412 nm412\text{ nm}412 nm on a bright background.
A single dark line at 456 nm456\text{ nm}456 nm on a bright background.
Dark lines at 412 nm412\text{ nm}412 nm and 462 nm462\text{ nm}462 nm on a bright background.
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.