10   14 The diagram shows the spectra produced by two stars. Spectrum A is produced from the light from the Sun and spectrum B is produced from the light from a distant star. 400 500 600 700 Spectrum A Spectrum B λ / nm The dark lines are produced when light from the core of the star is absorbed by hydrogen atoms in the outer regions of the star. Light is then re-radiated, but in all directions, giving rise to the dark lines in the spectrum. (a) Explain why the long wavelength lines are shifted by a greater amount than the short wavelength lines. 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(b) One of the lines in the hydrogen spectrum occurs at a wavelength of 656 nm in the laboratory. Explain what conclusion can be made from the shift in wavelength of this line in spectrum B. Your answer should include a calculation. 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(Total for Question 14 = 6 marks) Turn over 11   15 Aluminium is one of the most widely recycled metals. Aluminium cans are heated from room temperature until all the aluminium has melted. The molten aluminium is then used to make new cans. This process uses only 5% of the energy needed to extract aluminium from raw materials. On a website it is claimed that recycling one aluminium can of mass 14 g saves enough energy to listen to music on a mobile phone continuously for 7 days. Assess the validity of this claim. melting point of aluminium = 660 K specific heat capacity of aluminium = 902 J kg−1 K−1 specific latent heat of aluminium = 396 kJ kg−1 room temperature = 293 K mobile phone p.d. = 3.7 V mobile phone current = 120 mA .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. (Total for Question 15 = 6 marks)