COSMIC MICROWAVE BACKGROUND (CMB) RADIATION
2 marks · NormalWhat is meant by the term ‘red-shift’ and what does it suggest about the universe?
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Red-shift is when light from distant galaxies is shifted to longer wavelengths. It suggests that the universe is expanding.
Also accept: Red-shift means light is stretched due to galaxies moving away; this implies the universe is expanding.
Common mistakes: red-shift means frequency increases; red-shift happens when objects move towards us
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Marking points
B1 · 1 mark · Defines red-shift as stretching of light to longer wavelength.
B2 · 1 mark · Links red-shift to the idea of an expanding universe.
Worked solution
Red-shift is the shift of light to longer wavelengths when an object moves away from us. This suggests the universe is expanding.