Pearson Edexcel International GCSE in Physics · 4PH1 · Free · no account needed
Red-Shift — exam questions
10 original Incandio exam-style questions on red-Shift, 24 marks, about 24 minutes of writing. Each one carries the command word, the tariff and the specification statement it assesses, exactly as a paper presents them. This is an original Incandio practice question, written to reflect the structure and demands of the qualification. It is not an official Pearson Edexcel past-paper question.
This is the practice set for Red-Shift — the lesson that teaches it. Read the lesson first if the idea is new; come here when you want to find out whether you can turn it into marks. Completely free, no account needed to read.
What these questions ask of you
8 command words run through this set, and on Pearson Edexcel International GCSE Physics each one means something precise. Answering the wrong command is the commonest way a candidate who understands the lesson still loses the mark.
- Which (1 mark)
- one option chosen from the set given
- State (1 mark)
- one precise fact or definition
- Name (1 mark)
- the correct quantity, unit or component
- Calculate (1–5 marks)
- select the equation, substitute, evaluate — and state the unit Misread as: giving a bare number with no equation and no unit
- Describe (2–4 marks)
- developed, linked statements of what happens — including a named direction where one exists
- Explain (2–4 marks)
- the physics that causes it, set out as a line of reasoning Misread as: describing the change without giving the physical reason for it
- Suggest (1–3 marks)
- a plausible answer applying taught physics to an unfamiliar arrangement
- Determine (1–4 marks)
- a value obtained by combining a reading or gradient with a relationship
Assessed on Paper 1 (4PH1/1P) and Paper 2 (4PH1/2P), against AO1, AO2, AO3.
Where these sit in the specification
Pearson Edexcel International GCSE Physics (4PH1) — statements 8.15 · 8.17 · 8.16 · 8.18. Incandio is aligned to this specification; it is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording.
The 10 questions
Answer them on paper, then open the lesson's exam practice to have them marked. The mark scheme, the accepted and rejected answers and the annotated model answer are in Incandio and are not printed here — an answer beside its question is not practice.
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An observatory measured the red-shift of a hydrogen line in the spectra of four galaxies. The same line has a wavelength of 486.0 nm when measured in a laboratory on Earth. The speed of light is 3.0 × 10⁸ m/s.
Table 1 — the hydrogen line observed in four galaxies Galaxy Observed wavelength / nm Distance / millions of light years W 487.6 30 X 490.9 100 Y 494.1 160 Z 502.2 310 (a)
(2)Determine
Determine the change in wavelength for galaxy X, using Table 1.
An observatory measured the red-shift of a hydrogen line in the spectra of four galaxies. The same line has a wavelength of 486.0 nm when measured in a laboratory on Earth. The speed of light is 3.0 × 10⁸ m/s.
Table 1 — the hydrogen line observed in four galaxies Galaxy Observed wavelength / nm Distance / millions of light years W 487.6 30 X 490.9 100 Y 494.1 160 Z 502.2 310 change = ............................ nm
(b)
(3)Calculate
Calculate the speed at which galaxy X is receding, using Table 1.
An observatory measured the red-shift of a hydrogen line in the spectra of four galaxies. The same line has a wavelength of 486.0 nm when measured in a laboratory on Earth. The speed of light is 3.0 × 10⁸ m/s.
Table 1 — the hydrogen line observed in four galaxies Galaxy Observed wavelength / nm Distance / millions of light years W 487.6 30 X 490.9 100 Y 494.1 160 Z 502.2 310 speed = ............................ m/s
(c)
(3)Explain
Explain what Table 1 shows about the universe.
An observatory measured the red-shift of a hydrogen line in the spectra of four galaxies. The same line has a wavelength of 486.0 nm when measured in a laboratory on Earth. The speed of light is 3.0 × 10⁸ m/s.
Table 1 — the hydrogen line observed in four galaxies Galaxy Observed wavelength / nm Distance / millions of light years W 487.6 30 X 490.9 100 Y 494.1 160 Z 502.2 310 (Total for Question 1 = 8 marks)
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(1)Which
Which change to the light from a galaxy shows that it is moving away from the Earth?
Change A an increase in wavelength B a decrease in wavelength C an increase in speed D no change at all (Total for Question 2 = 1 mark)
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(1)State
State how the red-shift of a galaxy is related to its distance from the Earth.
(Total for Question 3 = 1 mark)
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(1)Name
Name the shift observed in the light from a galaxy that is moving towards the Earth.
(Total for Question 4 = 1 mark)
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(4)Calculate
A spectral line of reference wavelength 600.0 nm is observed at 606.0 nm in a distant galaxy. Calculate the speed at which the galaxy is receding. The speed of light is 3.0 × 10⁸ m/s.
speed = ............................ m/s
(Total for Question 5 = 4 marks)
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(3)Describe
Describe how astronomers can tell that a spectral line has been red-shifted.
Figure 1 — the spectrum of a distant galaxy (Total for Question 6 = 3 marks)
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(3)Explain
Explain why the red-shift of distant galaxies is taken as evidence that the universe is expanding rather than that the Earth is at the centre of everything.
(Total for Question 7 = 3 marks)
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(3)Suggest
Suggest why this observation does not contradict the theory that the universe is expanding.
A galaxy coming towards us — The Andromeda galaxy is one of the Milky Way's nearest neighbours, about 2.5 million light years away. Its light is blue-shifted: it is approaching us at around 110 km/s and will eventually collide with our own galaxy. Almost every galaxy beyond the immediate neighbourhood is red-shifted.
(Total for Question 8 = 3 marks)
Have them marked, then defend the answer
Practice tells you the mark; teaching it back tells you whether you understand it. On Incandio a topic counts as mastered only once you have taught it and defended it.
- Mark these questions — 10 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain red-Shift to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Christian Doppler over three rounds, marked against descriptors you can read first.
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Back to the lesson
- Red-Shift — Every distant galaxy is running away from us, the far ones fastest — and why that does not put us at the centre of anything.
- All of Incandio Physics · Incandio Exam Practice