IGCSE Physics Edexcel 4PH1

describe the past evolution of the universe and the main arguments in favour of the Big Bang

describe evidence that supports the Big Bang theory (red-shift and cosmic microwave background (CMB) radiation)

describe that if a wave source is moving relative to an observer there will be a change in the observed frequency and wavelength

use the equation relating change in wavelength, wavelength, velocity of a galaxy and the speed of light:

$\dfrac{\text{change in wavelength}}{\text{reference wavelength}} = \dfrac{\text{velocity of a galaxy}}{\text{speed of light}}$

$\dfrac{λ-λ_0}{λ_0} = \dfrac{Δλ}{λ_0} = \dfrac{v}{c}$

describe the red-shift in light received from galaxies at different distances away from the Earth

explain why the red-shift of galaxies provides evidence for the expansion of the universe