Physics · AQA 7408 · Option A · Topic 3.9

Astrophysics

Option: telescopes, how stars are classified, the Hertzsprung–Russell diagram, and cosmology.

  • 14 sub-topics
  • Taught in Year 13
  • 95 practice questions
  • 14 animated lessons
Practice questions (95) Lessons Worksheets All AQA Physics topics

What the specification says

Every sub-topic AQA can examine in this topic, with its reference number from the official specification. The Y12 and Y13 tags show when each sub-topic is usually taught.

  1. 3.9.1 Telescopes
  2. 3.9.1.1Astronomical telescope consisting of two converging lensesY13
  3. 3.9.1.2Reflecting telescopesY13
  4. 3.9.1.3Single dish radio telescopes, I-R, U-V and X-ray telescopesY13
  5. 3.9.1.4Advantages of large diameter telescopesY13
  6. 3.9.2 Classification of stars
  7. 3.9.2.1Classification by luminosityY13
  8. 3.9.2.2Absolute magnitude, MY13
  9. 3.9.2.3Classification by temperature, black-body radiationY13
  10. 3.9.2.4Principles of the use of stellar spectral classesY13
  11. 3.9.2.5The Hertzsprung-Russell (HR) diagramY13
  12. 3.9.2.6Supernovae, neutron stars and black holesY13
  13. 3.9.3 Cosmology
  14. 3.9.3.1Doppler effectY13
  15. 3.9.3.2Hubble's lawY13
  16. 3.9.3.3QuasarsY13
  17. 3.9.3.4Detection of exoplanetsY13

Try 3 questions

Easy, medium and hard questions from this topic, each with a worked solutions and the mark for every step. All 95 questions in this topic, free, no account needed.

Thermodynamics

Not needed for Year 12Easy

Black body radiation · Year 13 · 3 marks

A black body is heated from 3000 K to 6000 K.
  1. (a)
    Define a black body.
    (1)
  2. (b)
    Describe two changes to its emission spectrum.
    (2)
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Part (a)1 mark

  1. A body that absorbs all the radiation that falls on it.

Part (b)2 marks

  1. The peak moves to a shorter wavelength.
  2. The intensity at every wavelength (and the total power) increases.

Total3

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  • A
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Space

Not needed for Year 12Medium

Intensity and luminosity · Year 13 · 3 marks

A star of luminosity 2.0×10252.0 \times 10^{25} W is 10 light years from Earth.
  1. Calculate the intensity of its radiation at Earth.
    (3)

Check your answer before you look at the solution

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  1. dd=9.46×1016 m{}= 9.46 \times 10^{16}\ \mathrm{m}
  2. I=L4πd2I = \frac{L}{4\pi d^2}
  3. II=1.78×10−10 W m−2{}= 1.78 \times 10^{-10}\ \mathrm{W\,m^{-2}}

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Astrophysics

Not needed for Year 12Hard

Balmer lines · Year 13 · 2 marks

  1. Why are hydrogen Balmer lines strongest in A-class stars?
    (2)
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  1. Hydrogen must be in the n=2n = 2 state to absorb Balmer lines.
  2. In A stars the temperature excites many atoms to n=2n = 2 without ionising them.

Total2

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  • B
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