# WPH15 Astrophysics and Cosmology Topic Questions

> Edexcel IAL WPH15: every Astrophysics and Cosmology topic question from 20 papers (2020–2026), grouped by syllabus point. 303 questions, 725 marks, with…

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Edexcel IAL · Physics · WPH15 · A Level

Every WPH15 Astrophysics and Cosmology topic question from the 2018–current syllabus, drawn from 20 papers (2020–2026) and grouped by syllabus point. Each row opens a page listing the exact question numbers, marks and a direct link into the paper. These are questions by topic, not full papers, so you can revise one topic at a time.

- WPH15
- 18 subtopics
- 303 topic questions
- 20 papers
- 725 tagged marks
- [Back to Astrophysics and Cosmology](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/)
- [All paper codes](https://www.examsci.com/topics/)

Core finding

**170 be able to use the equations for redshift … for a source of… is the most frequently assessed subtopic in Astrophysics and Cosmology, with 39 topic questions and 98 marks across 20 papers.** 160 be able to apply Newton's laws of motion and universal… follows with 34 topic questions and 107 marks. The topic contains 18 subtopics, 303 topic questions and 725 marks in total. Rows count only the parts tagged to that subtopic, keep the same colour in both charts and repeat paper count, tagged marks and year range in the native table.

## Topic question count and mark distribution

Subtopics are on the vertical axis and sorted from highest to lowest. Only the parts whose knowledge graph matches a subtopic are counted for it, and percentages are each row's share of the tagged total in that chart. A part tagged to several subtopics is counted in each bar, so the bars are not a partition of the topic total.

### Questions by subtopic

question items

- [170 be able to use the equations for redshift $z=\frac{\Delta\lambda}{\lambda}\approx\frac{\Delta f}{f}\approx\frac{v}{c}$ for a source of electromagnetic radiation moving relative to an observer and $v= H_{0}d$ for objects at cosmological distances](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/170-be-able-to-use-the-equations-for-redshift-z-frac-delta-lambda-lambda-approx-frac/) (20 papers) — 39 · 10.0%
- [160 be able to apply Newton's laws of motion and universal gravitation to orbital motion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/160-be-able-to-apply-newton-s-laws-of-motion-and-universal-gravitation-to-orbital/) (19 papers) — 34 · 8.7%
- [164 be able to use the equation, intensity $I=\frac{L}{4\pi d^{2}}$ where L is luminosity and d is distance from the source](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/164-be-able-to-use-the-equation-intensity-i-frac-l-4-pi-d-2-where-l-is-luminosity-and/) (18 papers) — 34 · 8.7%
- [158 be able to use the equation $V_{grav}=\frac{-Gm}{r}$ for a radial gravitational field](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/158-be-able-to-use-the-equation-v-grav-frac-gm-r-for-a-radial-gravitational-field/) (19 papers) — 29 · 7.4%
- [167 be able to sketch and interpret a simple Hertzsprung-Russell diagram that relates stellar luminosity to surface temperature](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/167-be-able-to-sketch-and-interpret-a-simple-hertzsprung-russell-diagram-that-relates/) (19 papers) — 29 · 7.4%
- [163 be able to use Wien's law equation $\lambda_{max}T=2.898\times10^{-3}\text{ m K}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/163-be-able-to-use-wien-s-law-equation-lambda-max-t-2-898-times10-3-text-m-k-for/) (20 papers) — 28 · 7.2%
- [168 understand how to relate the Hertzsprung-Russell diagram to the life cycle of stars](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/168-understand-how-to-relate-the-hertzsprung-russell-diagram-to-the-life-cycle-of/) (15 papers) — 26 · 6.7%
- [156 be able to use the equation $F=\frac{Gm_{1}m_{2}}{r^{2}}$ (Newton's law of universal gravitation)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/156-be-able-to-use-the-equation-f-frac-gm-1-m-2-r-2-newton-s-law-of-universal/) (15 papers) — 24 · 6.2%
- [157 be able to derive and use the equation $g=\frac{Gm}{r^{2}}$ for the gravitational field due to a point mass](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/157-be-able-to-derive-and-use-the-equation-g-frac-gm-r-2-for-the-gravitational-field/) (18 papers) — 23 · 5.9%
- [162 be able to use the Stefan-Boltzmann law equation $L=\sigma AT^{4}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/162-be-able-to-use-the-stefan-boltzmann-law-equation-l-sigma-at-4-for-black-body/) (20 papers) — 23 · 5.9%
- [166 understand how astronomical distances can be determined using measurements of intensity received from standard candles (objects of known luminosity)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/166-understand-how-astronomical-distances-can-be-determined-using-measurements-of/) (14 papers) — 19 · 4.9%
- [171 understand the controversy over the age and ultimate fate of the universe associated with the value of the Hubble constant and the possible existence of dark matter.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/171-understand-the-controversy-over-the-age-and-ultimate-fate-of-the-universe/) (14 papers) — 19 · 4.9%
- [165 understand how astronomical distances can be determined using trigonometric parallax](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/165-understand-how-astronomical-distances-can-be-determined-using-trigonometric/) (15 papers) — 18 · 4.6%
- [161 understand what is meant by a black body radiator and be able to interpret radiation curves for such a radiator](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/161-understand-what-is-meant-by-a-black-body-radiator-and-be-able-to-interpret/) (12 papers) — 16 · 4.1%
- [169 understand how the movement of a source of waves relative to an observer/detector gives rise to a shift in frequency (Doppler effect)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/169-understand-how-the-movement-of-a-source-of-waves-relative-to-an-observer-detector/) (12 papers) — 14 · 3.6%
- [154 understand that a gravitational field (force field) is defined as a region where a mass experiences a force](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/154-understand-that-a-gravitational-field-force-field-is-defined-as-a-region-where-a/) (4 papers) — 5 · 1.3%
- [155 understand that gravitational field strength is defined as $g=\frac{F}{m}$ and be able to use this equation](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/155-understand-that-gravitational-field-strength-is-defined-as-g-frac-f-m-and-be-able/) (5 papers) — 5 · 1.3%
- [159 be able to compare electric fields with gravitational fields](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/159-be-able-to-compare-electric-fields-with-gravitational-fields/) (5 papers) — 5 · 1.3%

### Marks by subtopic

marks

- [160 be able to apply Newton's laws of motion and universal gravitation to orbital motion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/160-be-able-to-apply-newton-s-laws-of-motion-and-universal-gravitation-to-orbital/) (19 papers) — 107 · 11.0%
- [170 be able to use the equations for redshift $z=\frac{\Delta\lambda}{\lambda}\approx\frac{\Delta f}{f}\approx\frac{v}{c}$ for a source of electromagnetic radiation moving relative to an observer and $v= H_{0}d$ for objects at cosmological distances](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/170-be-able-to-use-the-equations-for-redshift-z-frac-delta-lambda-lambda-approx-frac/) (20 papers) — 98 · 10.1%
- [164 be able to use the equation, intensity $I=\frac{L}{4\pi d^{2}}$ where L is luminosity and d is distance from the source](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/164-be-able-to-use-the-equation-intensity-i-frac-l-4-pi-d-2-where-l-is-luminosity-and/) (18 papers) — 92 · 9.5%
- [162 be able to use the Stefan-Boltzmann law equation $L=\sigma AT^{4}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/162-be-able-to-use-the-stefan-boltzmann-law-equation-l-sigma-at-4-for-black-body/) (20 papers) — 79 · 8.1%
- [163 be able to use Wien's law equation $\lambda_{max}T=2.898\times10^{-3}\text{ m K}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/163-be-able-to-use-wien-s-law-equation-lambda-max-t-2-898-times10-3-text-m-k-for/) (20 papers) — 76 · 7.8%
- [168 understand how to relate the Hertzsprung-Russell diagram to the life cycle of stars](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/168-understand-how-to-relate-the-hertzsprung-russell-diagram-to-the-life-cycle-of/) (15 papers) — 65 · 6.7%
- [156 be able to use the equation $F=\frac{Gm_{1}m_{2}}{r^{2}}$ (Newton's law of universal gravitation)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/156-be-able-to-use-the-equation-f-frac-gm-1-m-2-r-2-newton-s-law-of-universal/) (15 papers) — 62 · 6.4%
- [158 be able to use the equation $V_{grav}=\frac{-Gm}{r}$ for a radial gravitational field](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/158-be-able-to-use-the-equation-v-grav-frac-gm-r-for-a-radial-gravitational-field/) (19 papers) — 61 · 6.3%
- [167 be able to sketch and interpret a simple Hertzsprung-Russell diagram that relates stellar luminosity to surface temperature](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/167-be-able-to-sketch-and-interpret-a-simple-hertzsprung-russell-diagram-that-relates/) (19 papers) — 52 · 5.4%
- [157 be able to derive and use the equation $g=\frac{Gm}{r^{2}}$ for the gravitational field due to a point mass](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/157-be-able-to-derive-and-use-the-equation-g-frac-gm-r-2-for-the-gravitational-field/) (18 papers) — 50 · 5.1%
- [166 understand how astronomical distances can be determined using measurements of intensity received from standard candles (objects of known luminosity)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/166-understand-how-astronomical-distances-can-be-determined-using-measurements-of/) (14 papers) — 47 · 4.8%
- [165 understand how astronomical distances can be determined using trigonometric parallax](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/165-understand-how-astronomical-distances-can-be-determined-using-trigonometric/) (15 papers) — 41 · 4.2%
- [171 understand the controversy over the age and ultimate fate of the universe associated with the value of the Hubble constant and the possible existence of dark matter.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/171-understand-the-controversy-over-the-age-and-ultimate-fate-of-the-universe/) (14 papers) — 38 · 3.9%
- [169 understand how the movement of a source of waves relative to an observer/detector gives rise to a shift in frequency (Doppler effect)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/169-understand-how-the-movement-of-a-source-of-waves-relative-to-an-observer-detector/) (12 papers) — 34 · 3.5%
- [161 understand what is meant by a black body radiator and be able to interpret radiation curves for such a radiator](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/161-understand-what-is-meant-by-a-black-body-radiator-and-be-able-to-interpret/) (12 papers) — 33 · 3.4%
- [154 understand that a gravitational field (force field) is defined as a region where a mass experiences a force](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/154-understand-that-a-gravitational-field-force-field-is-defined-as-a-region-where-a/) (4 papers) — 13 · 1.3%
- [155 understand that gravitational field strength is defined as $g=\frac{F}{m}$ and be able to use this equation](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/155-understand-that-gravitational-field-strength-is-defined-as-g-frac-f-m-and-be-able/) (5 papers) — 12 · 1.2%
- [159 be able to compare electric fields with gravitational fields](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/159-be-able-to-compare-electric-fields-with-gravitational-fields/) (5 papers) — 11 · 1.1%

## Subtopic comparison matrix

Curriculum order is by syllabus number, then alphabetically. Every row links to the matching past-paper question list.

| Subtopic | Topic questions | Papers | Marks | Years | |
| --- | --- | --- | --- | --- | --- |
| **[154 understand that a gravitational field (force field) is defined as a region where a mass experiences a force](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/154-understand-that-a-gravitational-field-force-field-is-defined-as-a-region-where-a/)** | 5 | 4 | 13 | 2021–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/154-understand-that-a-gravitational-field-force-field-is-defined-as-a-region-where-a/) |
| **[155 understand that gravitational field strength is defined as $g=\frac{F}{m}$ and be able to use this equation](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/155-understand-that-gravitational-field-strength-is-defined-as-g-frac-f-m-and-be-able/)** | 5 | 5 | 12 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/155-understand-that-gravitational-field-strength-is-defined-as-g-frac-f-m-and-be-able/) |
| **[156 be able to use the equation $F=\frac{Gm_{1}m_{2}}{r^{2}}$ (Newton's law of universal gravitation)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/156-be-able-to-use-the-equation-f-frac-gm-1-m-2-r-2-newton-s-law-of-universal/)** | 24 | 15 | 62 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/156-be-able-to-use-the-equation-f-frac-gm-1-m-2-r-2-newton-s-law-of-universal/) |
| **[157 be able to derive and use the equation $g=\frac{Gm}{r^{2}}$ for the gravitational field due to a point mass](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/157-be-able-to-derive-and-use-the-equation-g-frac-gm-r-2-for-the-gravitational-field/)** | 23 | 18 | 50 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/157-be-able-to-derive-and-use-the-equation-g-frac-gm-r-2-for-the-gravitational-field/) |
| **[158 be able to use the equation $V_{grav}=\frac{-Gm}{r}$ for a radial gravitational field](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/158-be-able-to-use-the-equation-v-grav-frac-gm-r-for-a-radial-gravitational-field/)** | 29 | 19 | 61 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/158-be-able-to-use-the-equation-v-grav-frac-gm-r-for-a-radial-gravitational-field/) |
| **[159 be able to compare electric fields with gravitational fields](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/159-be-able-to-compare-electric-fields-with-gravitational-fields/)** | 5 | 5 | 11 | 2020–2025 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/159-be-able-to-compare-electric-fields-with-gravitational-fields/) |
| **[160 be able to apply Newton's laws of motion and universal gravitation to orbital motion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/160-be-able-to-apply-newton-s-laws-of-motion-and-universal-gravitation-to-orbital/)** | 34 | 19 | 107 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/160-be-able-to-apply-newton-s-laws-of-motion-and-universal-gravitation-to-orbital/) |
| **[161 understand what is meant by a black body radiator and be able to interpret radiation curves for such a radiator](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/161-understand-what-is-meant-by-a-black-body-radiator-and-be-able-to-interpret/)** | 16 | 12 | 33 | 2021–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/161-understand-what-is-meant-by-a-black-body-radiator-and-be-able-to-interpret/) |
| **[162 be able to use the Stefan-Boltzmann law equation $L=\sigma AT^{4}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/162-be-able-to-use-the-stefan-boltzmann-law-equation-l-sigma-at-4-for-black-body/)** | 23 | 20 | 79 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/162-be-able-to-use-the-stefan-boltzmann-law-equation-l-sigma-at-4-for-black-body/) |
| **[163 be able to use Wien's law equation $\lambda_{max}T=2.898\times10^{-3}\text{ m K}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/163-be-able-to-use-wien-s-law-equation-lambda-max-t-2-898-times10-3-text-m-k-for/)** | 28 | 20 | 76 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/163-be-able-to-use-wien-s-law-equation-lambda-max-t-2-898-times10-3-text-m-k-for/) |
| **[164 be able to use the equation, intensity $I=\frac{L}{4\pi d^{2}}$ where L is luminosity and d is distance from the source](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/164-be-able-to-use-the-equation-intensity-i-frac-l-4-pi-d-2-where-l-is-luminosity-and/)** | 34 | 18 | 92 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/164-be-able-to-use-the-equation-intensity-i-frac-l-4-pi-d-2-where-l-is-luminosity-and/) |
| **[165 understand how astronomical distances can be determined using trigonometric parallax](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/165-understand-how-astronomical-distances-can-be-determined-using-trigonometric/)** | 18 | 15 | 41 | 2021–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/165-understand-how-astronomical-distances-can-be-determined-using-trigonometric/) |
| **[166 understand how astronomical distances can be determined using measurements of intensity received from standard candles (objects of known luminosity)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/166-understand-how-astronomical-distances-can-be-determined-using-measurements-of/)** | 19 | 14 | 47 | 2021–2025 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/166-understand-how-astronomical-distances-can-be-determined-using-measurements-of/) |
| **[167 be able to sketch and interpret a simple Hertzsprung-Russell diagram that relates stellar luminosity to surface temperature](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/167-be-able-to-sketch-and-interpret-a-simple-hertzsprung-russell-diagram-that-relates/)** | 29 | 19 | 52 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/167-be-able-to-sketch-and-interpret-a-simple-hertzsprung-russell-diagram-that-relates/) |
| **[168 understand how to relate the Hertzsprung-Russell diagram to the life cycle of stars](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/168-understand-how-to-relate-the-hertzsprung-russell-diagram-to-the-life-cycle-of/)** | 26 | 15 | 65 | 2021–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/168-understand-how-to-relate-the-hertzsprung-russell-diagram-to-the-life-cycle-of/) |
| **[169 understand how the movement of a source of waves relative to an observer/detector gives rise to a shift in frequency (Doppler effect)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/169-understand-how-the-movement-of-a-source-of-waves-relative-to-an-observer-detector/)** | 14 | 12 | 34 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/169-understand-how-the-movement-of-a-source-of-waves-relative-to-an-observer-detector/) |
| **[170 be able to use the equations for redshift $z=\frac{\Delta\lambda}{\lambda}\approx\frac{\Delta f}{f}\approx\frac{v}{c}$ for a source of electromagnetic radiation moving relative to an observer and $v= H_{0}d$ for objects at cosmological distances](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/170-be-able-to-use-the-equations-for-redshift-z-frac-delta-lambda-lambda-approx-frac/)** | 39 | 20 | 98 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/170-be-able-to-use-the-equations-for-redshift-z-frac-delta-lambda-lambda-approx-frac/) |
| **[171 understand the controversy over the age and ultimate fate of the universe associated with the value of the Hubble constant and the possible existence of dark matter.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/171-understand-the-controversy-over-the-age-and-ultimate-fate-of-the-universe/)** | 19 | 14 | 38 | 2021–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/171-understand-the-controversy-over-the-age-and-ultimate-fate-of-the-universe/) |

## Browse every topic question

- [154 understand that a gravitational field (force field) is defined as a region where a mass experiences a force](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/154-understand-that-a-gravitational-field-force-field-is-defined-as-a-region-where-a/) — 5 question items · 4 papers — 13 marks · 2021–2026
- [155 understand that gravitational field strength is defined as $g=\frac{F}{m}$ and be able to use this equation](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/155-understand-that-gravitational-field-strength-is-defined-as-g-frac-f-m-and-be-able/) — 5 question items · 5 papers — 12 marks · 2020–2026
- [156 be able to use the equation $F=\frac{Gm_{1}m_{2}}{r^{2}}$ (Newton's law of universal gravitation)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/156-be-able-to-use-the-equation-f-frac-gm-1-m-2-r-2-newton-s-law-of-universal/) — 24 question items · 15 papers — 62 marks · 2020–2026
- [157 be able to derive and use the equation $g=\frac{Gm}{r^{2}}$ for the gravitational field due to a point mass](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/157-be-able-to-derive-and-use-the-equation-g-frac-gm-r-2-for-the-gravitational-field/) — 23 question items · 18 papers — 50 marks · 2020–2026
- [158 be able to use the equation $V_{grav}=\frac{-Gm}{r}$ for a radial gravitational field](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/158-be-able-to-use-the-equation-v-grav-frac-gm-r-for-a-radial-gravitational-field/) — 29 question items · 19 papers — 61 marks · 2020–2026
- [159 be able to compare electric fields with gravitational fields](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/159-be-able-to-compare-electric-fields-with-gravitational-fields/) — 5 question items · 5 papers — 11 marks · 2020–2025
- [160 be able to apply Newton's laws of motion and universal gravitation to orbital motion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/160-be-able-to-apply-newton-s-laws-of-motion-and-universal-gravitation-to-orbital/) — 34 question items · 19 papers — 107 marks · 2020–2026
- [161 understand what is meant by a black body radiator and be able to interpret radiation curves for such a radiator](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/161-understand-what-is-meant-by-a-black-body-radiator-and-be-able-to-interpret/) — 16 question items · 12 papers — 33 marks · 2021–2026
- [162 be able to use the Stefan-Boltzmann law equation $L=\sigma AT^{4}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/162-be-able-to-use-the-stefan-boltzmann-law-equation-l-sigma-at-4-for-black-body/) — 23 question items · 20 papers — 79 marks · 2020–2026
- [163 be able to use Wien's law equation $\lambda_{max}T=2.898\times10^{-3}\text{ m K}$ for black body radiators](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/163-be-able-to-use-wien-s-law-equation-lambda-max-t-2-898-times10-3-text-m-k-for/) — 28 question items · 20 papers — 76 marks · 2020–2026
- [164 be able to use the equation, intensity $I=\frac{L}{4\pi d^{2}}$ where L is luminosity and d is distance from the source](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/164-be-able-to-use-the-equation-intensity-i-frac-l-4-pi-d-2-where-l-is-luminosity-and/) — 34 question items · 18 papers — 92 marks · 2020–2026
- [165 understand how astronomical distances can be determined using trigonometric parallax](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/165-understand-how-astronomical-distances-can-be-determined-using-trigonometric/) — 18 question items · 15 papers — 41 marks · 2021–2026
- [166 understand how astronomical distances can be determined using measurements of intensity received from standard candles (objects of known luminosity)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/166-understand-how-astronomical-distances-can-be-determined-using-measurements-of/) — 19 question items · 14 papers — 47 marks · 2021–2025
- [167 be able to sketch and interpret a simple Hertzsprung-Russell diagram that relates stellar luminosity to surface temperature](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/167-be-able-to-sketch-and-interpret-a-simple-hertzsprung-russell-diagram-that-relates/) — 29 question items · 19 papers — 52 marks · 2020–2026
- [168 understand how to relate the Hertzsprung-Russell diagram to the life cycle of stars](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/168-understand-how-to-relate-the-hertzsprung-russell-diagram-to-the-life-cycle-of/) — 26 question items · 15 papers — 65 marks · 2021–2026
- [169 understand how the movement of a source of waves relative to an observer/detector gives rise to a shift in frequency (Doppler effect)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/169-understand-how-the-movement-of-a-source-of-waves-relative-to-an-observer-detector/) — 14 question items · 12 papers — 34 marks · 2020–2026
- [170 be able to use the equations for redshift $z=\frac{\Delta\lambda}{\lambda}\approx\frac{\Delta f}{f}\approx\frac{v}{c}$ for a source of electromagnetic radiation moving relative to an observer and $v= H_{0}d$ for objects at cosmological distances](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/170-be-able-to-use-the-equations-for-redshift-z-frac-delta-lambda-lambda-approx-frac/) — 39 question items · 20 papers — 98 marks · 2020–2026
- [171 understand the controversy over the age and ultimate fate of the universe associated with the value of the Hubble constant and the possible existence of dark matter.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/171-understand-the-controversy-over-the-age-and-ultimate-fate-of-the-universe/) — 19 question items · 14 papers — 38 marks · 2021–2026

## Other topics in WPH15

- [Nuclear Decay 178 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/)
- [Oscillations 145 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/oscillations/)
- [Thermodynamics 111 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/thermodynamics/)

## Topic question rules and edge cases

**How many subtopics does Astrophysics and Cosmology contain?**

This page lists 18 subtopics tagged to the current syllabus. They are ordered by syllabus number, then alphabetically, and each row opens a page of matching past-paper questions.

**How are the subtopic question and mark totals calculated?**

A multiple-choice question contributes one item and its marks to every subtopic it is tagged with. A structured question contributes one item per tagged part, and that part’s marks; untagged parts of the same question are not counted here. A part tagged to several subtopics therefore appears under each of them.

**Why do some subtopics have no numbered prefix?**

Practical-skills statements and some syllabus bullets are unnumbered. Numbered statements come first; unnumbered statements and ties are sorted alphabetically.

**Is the LaTeX rendered without JavaScript?**

Yes. Subtopics that contain formulas are converted to static KaTeX HTML during the build, and the KaTeX stylesheet is served from the same site.

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Full page with native tables, bar charts and Practice Hub links: https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/