1.	Charge coupled devices can have an efficiency as great as 70% compared with photographic film which has an efficiency of less than 5%. State two advantages of this greater efficiency.
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(b)	(i)	Give three other advantages that charge coupled devices (CCDs) have compared with photographic emulsions.
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Advantage 3 .......................................................................................................	(3)
(ii)	Give one disadvantage of CCDs compared with photographic emulsions.
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2. “Red stars are cooler than blue stars” Use Wein’s Law to demonstrate that this statement must be true.

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Star	λmax	
α Orionis	475nm	
β Orionis	755nm	
γ Orionis	685nm	

b) The table shows some of stars in a given constellation and the wavelength of maximum intensity for each. Calculate the surface temperature of each of the stars
α Orionis. ……………………………………………………………………………………………………
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β Orionis……………………………………………………………………………………………
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γ Orionis……………………………………………………………………………………………
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3. a) What is the wavelength of maximum intensity produced by the Sun (surface temperature 5700K)
 Sketch an intensity at any given wavelength/wavelength graph for the Sun			(3)

b) Use Wien’s law,  = 3.9 × 10–3 m K, to estimate the wavelength at which the intensity of radiation from the Earth is a maximum.
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c)	Add a second curve to the graph to show the approximate energy distribution in the radiation emitted by the Earth.							(2)

d)	The Sun has become slightly more yellow during its lifetime. It used to be more orange in colour. It’s temperature has increased by 10% over the years.

Use Wien’s law to calculate the decrease in the wavelength of the peak intensity.
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4.	(a)	Charge coupled devices (CCDs) have a higher efficiency than photographic emulsion. Explain what is meant by the term ‘higher efficiency’. State one advantage of this higher efficiency.
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(3)
(b)	The satellite COBE was launched in 1989 to investigate the cosmic background radiation. COBE detected the peak in the spectrum of the background radiation at a wavelength of 1.1 × 10–3 m. Use this value to calculate the temperature of space.
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(2)

	To what part of the electromagnetic spectrum does radiation of wavelength 1.1 × 10–3 m belong?
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(c)	State two ways in which a white dwarf star differs from a main sequence star.
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	Describe what happens to a star after it has become a white dwarf.
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(2)
	A Hertzsprung-Russell diagram showing the main sequence is drawn below. The luminosity of the Sun = .

	Add a scale to the temperature axis.
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	Identify one star on the diagram which has a luminosity very similar to that of the Sun. Label this star X.
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	Shade in a region on the diagram where white dwarf stars are located. Label this region W.
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	Label with an M the region on the diagram where the most massive main sequence stars are located.
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	Explain why the most massive main sequence stars have the shortest lifetimes. You may be awarded a mark for the clarity of your answer.
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(4)
(d)	Two stars, Deneb and Vega, are similar in colour. What can be deduced about the surface temperatures of the two stars? Explain your answer.
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(2)
	The table gives some information about the two stars.
Star	Luminosity/W	Distance from Earth/m	
Deneb	2.5 × 1031	1.5 × 1019	
Vega	1.9 × 1028	2.3 × 1017	

	Which star has the greater surface area? Justify your answer.
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	Which star will have the higher intensity and therefore appear brighter as seen from the Earth? Show all your working.
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(e)	The Gemini telescope on Hawaii has a diameter of 8.0 m; the Hubble space telescope has a diameter of 2.4 m. Show that Gemini has more than 10× the light gathering power of Hubble.
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	Give one situation in which large light-gathering power is important.
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	A telescope of diameter 100 m could be sunk into the ground. Suggest an operational disadvantage of having an extremely large telescope sunk into the ground.
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(1)
(Total 32 marks)