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The Earth's atmosphere absorbs electromagnetic radiation - Edexcel - GCSE Physics - Question 6 - 2012 - Paper 1
Question 6
The Earth's atmosphere absorbs electromagnetic radiation. The diagram shows how the amount absorbed changes with wavelength. How much of the visible light from spac... show full transcript
Worked Solution & Example Answer:The Earth's atmosphere absorbs electromagnetic radiation - Edexcel - GCSE Physics - Question 6 - 2012 - Paper 1
Step 1
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Step 3
Explain why scientists had to wait until the development of space flight before they could study this radiation in detail.
Answer
Cosmic background radiation at a wavelength of about 1 mm is absorbed by the Earth's atmosphere. Before the advent of space flight, it was impossible to observe this radiation effectively from the ground. Space flight allowed instruments to be placed above the atmosphere, enabling precise measurements of this essential evidence for the Big Bang Theory.
Step 4
Suggest why, when a galaxy has a very large red-shift, some of its visible light is not detected through the Earth's atmosphere.
Answer
A very large red-shift indicates that the light is stretched to longer wavelengths, potentially moving it into the infrared region or beyond, which is absorbed by the Earth's atmosphere. Hence, such light may not be detectable with traditional optical telescopes on Earth.
Step 5
Describe how careful observation of electromagnetic radiation from distant galaxies as well as from the whole of space gave evidence supporting the Big Bang.
Answer
Observations of electromagnetic radiation, including the cosmic microwave background radiation, provided evidence of the heat leftover from the Big Bang. The uniformity of this radiation across the universe and its spectrum supports the idea of an expanding universe. Furthermore, red-shift measurements show that galaxies are moving away from us, indicating that the universe is indeed expanding, a cornerstone of the Big Bang Theory.