Cosmology (Edexcel International A Level (IAL) Physics): Exam Questions

The diagram shows the Sun rotating about its axis as viewed from the Earth.

A, B and C are points on the surface of the Sun.

Light from points A, B and C is analysed. The wavelength λ_α of the alpha line in the hydrogen spectrum is determined for the light from each point.

Complete the table with the letters A, B and C to indicate the point corresponding to each wavelength.

Explain why there is a variation in the wavelength of the light from different points on the Sun.

In the laboratory, the wavelength of the alpha line in the hydrogen spectrum is 656.2797 nm.

Assess whether this is consistent with the Sun having a period of rotation approximately equal to 28 days.    

radius of the Sun = 7.0 × 10⁸ m    

1 day = 86 400 s

Explain how the observation of CMB radiation supports the Big Bang theory of the universe.

An astronomer observes a distant quasar with a redshift $z$ of $0.134$.

(i) Determine the distance, in $\text{m}$, from the Earth to the quasar.

$H_0=67{\text{ km s}}^{-1}{\text{ Mpc}}^{-1}$

$1\text{ pc}=3.1\times {10}^{16}\text{ m}$

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(ii) Suggest one reason why Hubble's law may not give a reliable value for the distance to such a remote object.

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