A LevelPhysicsEdexcelExam Questions10. SpaceAstronomy

Astronomy (Edexcel A Level Physics)

Exam Questions

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1a
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One of the largest stars in our galaxy is VY Canis Majoris. This star’s radius is 1420 times the radius of the Sun. The luminosity of this star is 270000 times the luminosity of the Sun.

A student states that the surface temperature of VY Canis Majoris must be much greater than the surface temperature of the Sun.


Determine whether the student’s statement is correct.

surface temperature of Sun = 5780 K
luminosity of Sun = 3.85 × 1026 W
radius of Sun = 6.96 × 108 m

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1b
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Calculate the wavelength with maximum intensity in the black body radiation spectrum of VY Canis Majoris.

Wavelength = ....................................................................

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1c
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Add the position of VY Canis Majoris to the Hertzsprung Russell diagram to determine which type of star it is.

q15c-nov-2021-9ph0-02-edexcel-as-a-level-phy

Type of star ....................................................................

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2a
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A Hertzsprung-Russell (HR) diagram shows how the luminosity L depends on the surface temperature T for a group of stars.

The HR diagram below is for a young star cluster.

q9-nov-2021-9ph0-03-edexcel-as-a-level-phy

i)
Explain how we can tell that the young star cluster is in the early stages of its evolution.

(2)

ii)
Explain why the most massive stars in the cluster have the greatest luminosities.

(4)

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2b
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The HR diagram on the previous page shows an approximately linear relationship for stars in this cluster.

i)
It is suggested that the relationship between luminosity L and surface temperature T is of the form

L space equals space k T to the power of n

where k and n are constants.

Explain why a graph of log L against log T would give a straight line.

(2)

ii)
The table shows data for stars in this cluster.

L / LSun T / K    
39.5 10 600    
545 16 400    
20 600 26 800    
535 000 44 900    
1 770 000 53 300    


Plot a graph of log L against log T on the grid below. Use the columns provided to show any processed data.

(5)

iii)
Determine a value for n.

(2)

 

n = .......................................................

q9biii-nov-2021-9ph0-03-edexcel-as-a-level-phy

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3a
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In 2016 the Breakthrough Starshot initiative was announced. This project intends to send a fleet of small probes to Proxima Centauri, the nearest star to the Sun. This journey would take about twenty years.

The radiation intensity at Earth from Proxima Centauri is 3.25 × 10-11 W m-2.
The luminosity of the Sun is LΘ .

i)
Show that the luminosity of Proxima Centauri is about 0.002 LΘ .

(3)

distance to Proxima Centauri = 4.00 × 1016 m
LΘ = 3.85 × 1026 W

ii)
Proxima Centauri is described on a website as a main sequence star.

Determine whether the surface temperature of Proxima Centauri is consistent with a position on the main sequence of the Hertzsprung-Russell diagram.

(3)

radius of Proxima Centauri = 9.81 × 107 m

q19aii-june-2018-9ph0-02-edexcel-as-a-level-phy

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3b
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The composition of a star can be determined by analysis of its absorption spectrum.

Explain why there are certain specific frequencies missing from the spectrum.

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3c
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Describe how the distance to nearby stars like Proxima Centauri is determined.

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1a
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Solar panels consisting of combinations of photovoltaic cells use energy in the radiation received from the Sun to generate electricity.

An advertisement for solar panels claims that the intensity of radiation from the Sun incident at the top of the Earth’s atmosphere is more than 2 kW m−2.

Assess the validity of this claim.

radius of Sun = 6.96 × 108 m

surface temperature of Sun = 5790 K

distance from Sun to Earth = 1.50 × 1011 m

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1b
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The average intensity of radiation from the Sun incident at the Earth’s surface over a 24-hour period has been determined to be 164 W m−2.

q11b-nov-2020-9ph0-03-edexcel-as-a-level-phy

i)
The average intensity of radiation from the Sun at the Earth’s surface is much less than the intensity incident at the top of the Earth’s atmosphere.

Explain why.

(4)

ii)
It is claimed that the area of solar panels needed to generate 100 GW of power is about 0.5% of the surface area of the Earth.

Assess the validity of this claim.

radius of Earth = 6.4 × 106 m

typical efficiency of solar panels = 25%

(4)

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1c
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Scientists are developing a space station equipped with large solar panels. The space station would be located in a geostationary orbit. The space station would transfer energy to Earth as microwaves.

i)
A space station in a geostationary orbit is above the equator and has a period of 24 hours.

Explain one advantage of locating the space station in a geostationary orbit.

(2)

ii)
Calculate the height h of the space station above the equator when it is in a geostationary orbit.

mass of Earth = 6.00 × 1024 kg

24 hours = 8.64 × 104 s

(4)






h = ....................................

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