OCR A Level Physics

Topic Questions

5.12 Cosmology

11 mark

The parallax angle for a star is 0.015 seconds of arc.

What is the distance in parsecs (pc) of the star from the Earth?

  • 67 pc

  • 133 pc

  • 220 pc

  • 2.1 × 1018 pc

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21 mark

In astronomy, distance can be measured in different units.

Which one of the following distances is the largest?

  • 4.22 × 1016 m

  • 1.91 pc

  • 3.42 ly

  • 593 AU

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31 mark

Which two quantities are related in Hubble’s law?

  • Distance and mass of galaxies.

  • Velocity and intensity of galaxies.

  • Distance and velocity of galaxies.

  • Distance and red shift of stars in our galaxy.

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11 mark

A spectral line corresponds to a wavelength λ1 in the laboratory. The same spectral line observed in the spectrum of a receding galaxy corresponds to a wavelength λ2.

The distance of the galaxy from the Earth is d. The speed of light in a vacuum is c.

What is the correct expression for the Hubble constant H0?

  • H subscript 0 space end subscript almost equal to space fraction numerator c open parentheses lambda subscript 2 space end subscript minus space lambda subscript 1 close parentheses over denominator d space lambda subscript 1 end fraction

  • H subscript 0 space end subscript almost equal to space fraction numerator c lambda subscript 1 over denominator d space open parentheses lambda subscript 2 space end subscript minus space lambda subscript 1 close parentheses end fraction

  • H subscript 0 space end subscript almost equal to space fraction numerator c lambda subscript 2 over denominator d lambda subscript 1 end fraction

  • H subscript 0 space end subscript almost equal to space fraction numerator c lambda subscript 1 over denominator d lambda subscript 2 end fraction

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21 mark

Recent analysis of the data collected from the Hubble and Gaia telescopes gave the Hubble constant a value of 73.5 kms–1 Mpc–1.

What is this value, written to 2 significant figures, in s–1?

  • 2.4 × 10–21 s–1

  • 2.4 × 10–18 s–1

  • 2.4 × 10–12 s–1

  • 2.4 × 1021 s–1

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11 mark

An astronomer analyses the light from a distant galaxy.
One of the spectral lines in the spectrum observed from the galaxy has wavelength 610 nm.
The same spectral line has a wavelength of 590 nm when measured in the laboratory.

What is the speed of this galaxy?

  • 9.8 × 106 ms–1

  • 1.0 × 107 ms–1

  • 2.9 × 108 ms–1

  • 3.0 × 108 ms–1

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