Lesson 3.9

3.9 Astrophysics: telescopes, classification of stars, cosmology Quiz: AQA Physics, Unit 9

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.9, Astrophysics: telescopes, classification of stars, cosmology: 20 multiple choice questions for the AQA Physics (7408), Unit 9: Astrophysics (A-level option), written with Revision Ninja.

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The 20 questions

  1. What is the minimum angular resolution theta for a telescope aperture diameter D and wavelength lambda?

    • lambda / D^2
    • lambda x D
    • D / lambda
    • lambda / D

  2. How does the light-collecting power of an astronomical telescope depend on its objective diameter D?

    • Proportional to D^3
    • Inversely proportional
    • Proportional to D^2
    • Proportional to D

  3. Which formula gives the angular magnification M of a refracting telescope in normal adjustment?

    • fo + fe
    • fo x fe
    • fo / fe
    • fe / fo

  4. What type of secondary mirror is used in a Cassegrain reflecting telescope?

    • Convex mirror
    • Plane mirror
    • Paraboloid lens
    • Concave mirror

  5. Which optical aberration affects refracting telescopes but does not affect reflecting telescopes?

    • Coma
    • Chromatic aberration
    • Spherical aberration
    • Astigmatism

  6. A star's apparent magnitudes differ by 1. What is the ratio of their brightnesses?

    • about 10
    • about 1.58
    • about 100
    • about 2.51

  7. Which equation relates apparent magnitude m, absolute magnitude M and distance d in parsecs?

    • m + M = 5 log10(d)
    • m - M = 5 log10(d / 10)
    • m - M = log10(d) / 5
    • m - M = 5 log10(10 / d)

  8. A star has apparent magnitude 6 at a distance of 100 parsecs. What is its absolute magnitude?

    • 6
    • -1
    • 11
    • 1

  9. A star has a peak wavelength of 500 nm in its black-body spectrum. Using Wien's displacement law with constant 2.9 x 10^-3 m K, what is its surface temperature?

    • 5800 K
    • 5.8 x 10^6 K
    • 580 K
    • 2900 K

  10. Two stars have the same surface temperature, but one has twice the radius of the other. What is the ratio of their power outputs?

    • 4 : 1
    • 1 : 1
    • 2 : 1
    • 8 : 1

  11. A galaxy has a recession speed of 7000 km/s. Using Hubble's constant H0 = 70 km/s per Mpc, what is its distance?

    • 490 Mpc
    • 100 Mpc
    • 7000 Mpc
    • 10 Mpc

  12. A galaxy has redshift z = 0.01 for a recession speed much less than c. What is its recession speed?

    • 30 km/s
    • 30 000 km/s
    • 3000 km/s
    • 300 km/s

  13. What is the approximate Schwarzschild radius of a black hole with the mass of the Sun?

    • about 3 m
    • about 30 km
    • about 3 km
    • about 300 m

  14. What parameter at the event horizon of a black hole equals the speed of light?

    • Orbital velocity
    • Phase velocity
    • Terminal velocity
    • Escape velocity

  15. Why can Type 1a supernovae be used as standard candles to measure astronomical distances?

    • Variable light output
    • High orbital speed
    • Known peak magnitude
    • Constant apparent brightness

  16. Using Hubble's constant H0 = 70 km/s per Mpc, what is the approximate age of the Universe if H0 is assumed constant?

    • about 140 billion years
    • about 4.6 billion years
    • about 1.4 billion years
    • about 14 billion years

  17. A spectral line at 500 nm shifts by 0.02 nm due to the Doppler effect. What is the speed of the source?

    • 1.2 km/s
    • 0.12 km/s
    • 12 km/s
    • 120 km/s

  18. What is the minimum angular resolution of a 2.5 m diameter telescope observing light of wavelength 500 nm?

    • 5.0 x 10^-7 rad
    • 8.0 x 10^-8 rad
    • 2.0 x 10^-7 rad
    • 2.0 x 10^-5 rad

  19. What property of a CCD describes the percentage of incident photons detected?

    • Quantum efficiency
    • Focal length
    • Magnification
    • Resolving power

  20. If a transiting planet reduces a star's brightness by 1%, what fraction is the planet's radius?

    • 0.1
    • 0.2
    • 0.001
    • 0.01

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