CAIE A-Level Physics 25.3.4 Hubble's Law and the Big Bang

Practise using Hubble’s law v = H0d to calculate speed, distance or Hubble constant and explaining how galactic recession supports an expanding Universe and the Big Bang.

Exam points

use v ≈ H₀d to calculate recession speed, distance or Hubble constant
explain how Hubble’s law supports an expanding Universe and the Big Bang theory

[Maximum number: 2]

A spectral line from a star within a galaxy is observed to have a wavelength of 660.9 nm . The same spectral line measured in the laboratory is observed to have a wavelength of 656.3 nm .

Calculate the distance to the star.

The Hubble constant is $2.3 \times 10^{-18} \mathrm{~s}^{-1}$ .
distance = m

$v=H_{0} d$

C1

$\begin{aligned} d =2.1 \times 10^{6} / 2.3 \times 10^{-18} =9.1 \times 1023 \mathrm{~m} \end{aligned}$

A1

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25.3.4—Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory question 1