# Topic Questions: 45 know and understand that at the interface between medium 1 and medium 2 $n_{1}\sin \theta_{1}= n_{2}\sin \theta_{2}$ where refractive index is $n=\frac{c}{v}$ — WPH12 Waves and Particle Nature of Light > 56 WPH12 Waves and Particle Nature of Light topic questions (147 marks) on 45 know and understand that at the interface… — 22 papers, 2019–2026. Open the… - Canonical HTML: https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/45-know-and-understand-that-at-the-interface-between-medium-1-and-medium-2-n-1-sin/ - Markdown mirror: https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/45-know-and-understand-that-at-the-interface-between-medium-1-and-medium-2-n-1-sin/index.md --- Edexcel IAL · Physics · WPH12 · Waves and Particle Nature of Light 56 WPH12 Waves and Particle Nature of Light topic questions are tagged to this syllabus point across 22 papers (2019–2026). Only the parts whose knowledge graph matches this syllabus statement are counted, and the table shows which parts of each question are involved. - 56 topic questions - 22 papers - 147 tagged marks - 12.0% of topic questions - 12.9% of topic marks - 2019–2026 - Syllabus 2018–current - [All WPH12 Waves and Particle Nature of Light topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/) - [All paper codes](https://www.examsci.com/topics/) Core finding **This Waves and Particle Nature of Light syllabus point appears in 22 WPH12 papers across 2019–2026, contributing 56 topic questions and 147 marks.** The most recent appearance is WPH12/01 January 2026. That equals 12.0% of the 468 topic questions and 12.9% of the 1,138 marks tagged to Waves and Particle Nature of Light. Only parts tagged to this subtopic are counted, so a four-part question can contribute one item and one part's marks. The table lists every matching question, its tagged parts and marks, with a link back to the paper page. Sessions are newest first, so the statement can be traced back through the full paper history. ## Topic questions by session Newest sessions first. Parts and marks count only the parts tagged to this subtopic; “x of y parts” shows how much of the question is tagged elsewhere. Select the paper cell to open the matching question on the paper page, or use **Go to Practice Hub** to answer that exact question in the Interactive Practice Hub. | Paper | Question | Type | Parts | Marks | Difficulty | Practice | | --- | --- | --- | --- | --- | --- | --- | | [**WPH12/01** January 2026 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2026-january-wph12-01/#q-20) | **Q20** Glycerol Refractometer Experiment - Edexcel IAL Physics Jan 2026 Q20 | FRQ | 3 parts ((a)(i), (a)(ii), (b)) | 8 | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=f217f3ed-8314-4b5a-a273-52fcc7614327&question_id=b59dcb56-510f-47bf-ad85-2c25a54adf98&source_detail=WPH12%2F01+January+2026) | | [**WPH12/02** January 2026 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2026-january-wph12-02/#q-16) | **Q16** Refractive Index and Dipstick Optical Mechanics - Edexcel IAL Physics Jan 2026 Q16 | FRQ | 2 of 3 parts ((a), (b)) | 6 of 10 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=b8583b90-86ed-4ac4-a0d0-fbc38baea73c&question_id=150d396d-f832-43ad-8cd5-60a936e87adb&source_detail=WPH12%2F02+January+2026) | | [**WPH12/02** January 2026 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2026-january-wph12-02/#q-18) | **Q18** Oceanic Acoustics Refraction - Edexcel IAL Physics Jan 2026 Q18 | FRQ | 1 of 3 parts ((a)) | 5 of 9 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=b8583b90-86ed-4ac4-a0d0-fbc38baea73c&question_id=e1f68c55-a8a4-458b-874b-fc8b1447fe67&source_detail=WPH12%2F02+January+2026) | | [**WPH12/01** October 2025 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2025-october-wph12-01/#q-14) | **Q14** Refraction in a Semicircular Glass Block - Edexcel IAL Physics Oct 2025 Q14 | FRQ | 3 of 4 parts ((a), (b)(i), (b)(ii)) | 4 of 8 on the paper | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=aca64168-b3d6-4595-86da-ac59e5bcce63&question_id=dc1225e2-352f-42db-ad98-c6cc68356030&source_detail=WPH12%2F01+October+2025) | | [**WPH12/02** October 2025 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2025-october-wph12-02/#q-13) | **Q13** Refractive Index dispersion in Glass Block - Edexcel IAL Physics Oct 2025 Q13 | FRQ | 2 parts ((a), (b)) | 9 | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=b2ad8e92-c12e-4023-a9f4-c72ce8345efa&question_id=09c80157-f246-4fb0-be58-8d5816138232&source_detail=WPH12%2F02+October+2025) | | [**WPH12/01** June 2025 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2025-june-wph12-01/#q-1) | **Q1** Speed of Light in Vegetable Oil - Edexcel IAL Physics May 2025 Q1 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3315043e-2e64-48db-9a4f-db8056c87e15&question_id=02645cdc-bcaf-4f26-838d-afe2cba2fec3&source_detail=WPH12%2F01+June+2025) | | [**WPH12/01** June 2025 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2025-june-wph12-01/#q-12) | **Q12** Snell's Law and Polarisation with Ray Box - Edexcel IAL Physics May 2025 Q12 | FRQ | 2 of 4 parts ((a)(i), (a)(ii)) | 3 of 9 on the paper | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3315043e-2e64-48db-9a4f-db8056c87e15&question_id=76827023-6803-48d5-9270-13462b669237&source_detail=WPH12%2F01+June+2025) | | [**WPH12/01** January 2025 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2025-january-wph12-01/#q-18) | **Q18** Light Propagation and Cladding in Optical Fibres - Edexcel IAL Physics Jan 2025 Q18 | FRQ | 1 of 4 parts ((a)) | 3 of 13 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e619207f-bc85-4481-9d5b-1fbdc31ada66&question_id=687fae2c-a61f-4bac-9c52-6a8bf3db9b32&source_detail=WPH12%2F01+January+2025) | | [**WPH12/01** October 2024 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2024-october-wph12-01/#q-17) | **Q17** Refraction and Total Internal Reflection - Edexcel IAL Physics Oct 2024 Q17 | FRQ | 2 parts ((a), (b)) | 8 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=ed4e8373-fe1b-4450-b59f-13747d878e02&question_id=5184bfd0-7fa7-4c5c-964e-a5fbd07b371d&source_detail=WPH12%2F01+October+2024) | | [**WPH12/01** June 2024 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2024-june-wph12-01/#q-3) | **Q3** Refractive Index at Boundary - Edexcel IAL Physics June 2024 Q3 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=faa19ed2-c4f7-4432-9548-86e4a8a1dac4&question_id=68026cc6-c254-4962-8249-893c5a1f309c&source_detail=WPH12%2F01+June+2024) | | [**WPH12/01** June 2024 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2024-june-wph12-01/#q-18) | **Q18** Camera Prism Optics & Sensor Quantum Detection - Edexcel IAL Physics June 2024 Q18 | FRQ | 1 of 4 parts ((a)) | 2 of 13 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=faa19ed2-c4f7-4432-9548-86e4a8a1dac4&question_id=845773b9-da1f-4967-ad55-530913c9d4f2&source_detail=WPH12%2F01+June+2024) | | [**WPH12/01** January 2024 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2024-january-wph12-01/#q-1) | **Q1** Refraction and Reflection - Edexcel IAL Physics Jan 2024 Q1 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=030444a8-988a-46b6-9902-c76464e7c5f1&question_id=f6ed86b3-5042-4434-a03c-0a58f1d44331&source_detail=WPH12%2F01+January+2024) | | [**WPH12/01** January 2024 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2024-january-wph12-01/#q-13) | **Q13** Hydro-beads Refractive Index - Edexcel IAL Physics Jan 2024 Q13 | FRQ | 2 of 3 parts ((a), (b)(i)) | 4 of 7 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=030444a8-988a-46b6-9902-c76464e7c5f1&question_id=dd72b24d-f72d-46cd-954c-60813b6a3c3d&source_detail=WPH12%2F01+January+2024) | | [**WPH12/01** October 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-october-wph12-01/#q-1) | **Q1** Diffraction Grating Formula Units - Edexcel IAL Physics Oct 2023 Q1 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3e216bad-b45b-4b54-ad64-443f4188aa4c&question_id=1f2293cc-80c4-425f-9d7d-9f5e8c7e7428&source_detail=WPH12%2F01+October+2023) | | [**WPH12/01** October 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-october-wph12-01/#q-16) | **Q16** Solar Cell Thin Coating and Efficiency - Edexcel IAL Physics Oct 2023 Q16 | FRQ | 1 of 3 parts ((b)) | 4 of 11 on the paper | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3e216bad-b45b-4b54-ad64-443f4188aa4c&question_id=7b61fa25-b1fc-4b7d-a3dd-bcbb0063c82f&source_detail=WPH12%2F01+October+2023) | | [**WPH12/01** October 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-october-wph12-01/#q-18) | **Q18** Snell's Law, Wavefronts and Critical Angle - Edexcel IAL Physics Oct 2023 Q18 | FRQ | 2 of 4 parts ((a), (b)) | 7 of 14 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3e216bad-b45b-4b54-ad64-443f4188aa4c&question_id=83d8c60c-f85b-4562-81fb-2ffe50f6d30b&source_detail=WPH12%2F01+October+2023) | | [**WPH12/01** June 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-june-wph12-01/#q-3) | **Q3** Refraction of Monochromatic Light - Edexcel IAL Physics May 2023 Q3 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3a8e11e5-0ef0-468b-b140-32d6d8e746b5&question_id=c585f2a2-8e70-453c-8bcd-678e91611fd8&source_detail=WPH12%2F01+June+2023) | | [**WPH12/01** June 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-june-wph12-01/#q-13) | **Q13** Refractive Index and Polarisation - Edexcel IAL Physics May 2023 Q13 | FRQ | 1 of 3 parts ((a)) | 3 of 8 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3a8e11e5-0ef0-468b-b140-32d6d8e746b5&question_id=8d782db7-7dd5-4787-a26f-67ee854c8ef4&source_detail=WPH12%2F01+June+2023) | | [**WPH12/01** January 2023 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2023-january-wph12-01/#q-12) | **Q12** Refractive Index of Glass - Edexcel IAL Physics Jan 2023 Q12 | FRQ | 3 parts ((a)(i), (a)(ii), (b)) | 6 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=44f43e47-e4db-4cf8-926d-d8e4e0a15c3a&question_id=11352af2-7d0d-4544-b485-26f3b3792527&source_detail=WPH12%2F01+January+2023) | | [**WPH12/01** October 2022 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2022-october-wph12-01/#q-8) | **Q8** Light Interactions with Glass Block - Edexcel IAL Physics Oct 2022 Q8 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=beffb6bb-3877-4d0b-b853-45356f31e525&question_id=6adddee0-7733-4898-8e75-3d7f1b5641d1&source_detail=WPH12%2F01+October+2022) | | [**WPH12/01** October 2022 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2022-october-wph12-01/#q-16) | **Q16** Optical Fibres and Total Internal Reflection - Edexcel IAL Physics Oct 2022 Q16 | FRQ | 2 of 4 parts ((a)(i), (b)(i)) | 6 of 11 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=beffb6bb-3877-4d0b-b853-45356f31e525&question_id=dc5d841a-f006-4f1a-a36e-e59367ceda66&source_detail=WPH12%2F01+October+2022) | | [**WPH12/01** June 2022 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2022-june-wph12-01/#q-11) | **Q11** Refraction and Critical Angle in Glass - Edexcel IAL Physics June 2022 Q11 | FRQ | 2 parts ((a), (b)) | 8 | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=3069ad40-1aa5-4af5-a2d4-5c7bfc121c7d&question_id=17dab5ef-b36c-484b-b82e-f062b0ff7bd9&source_detail=WPH12%2F01+June+2022) | | [**WPH12/01** January 2022 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2022-january-wph12-01/#q-5) | **Q5** Light Refraction in Multiple Media - Edexcel IAL Physics Jan 2022 Q5 | MCQ | MCQ · 1 part | 1 | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=272cf6d5-ace3-46e9-81c3-821d84b7c606&question_id=e61ae0fe-e7d8-4ce6-b2bb-a129124acc56&source_detail=WPH12%2F01+January+2022) | | [**WPH12/01** January 2022 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2022-january-wph12-01/#q-16) | **Q16** Wave Properties, Refraction and Polarisation - Edexcel IAL Physics Jan 2022 Q16 | FRQ | 3 of 5 parts ((b)(i), (b)(ii), (b)(iii)) | 8 of 12 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=272cf6d5-ace3-46e9-81c3-821d84b7c606&question_id=ddf7da0b-05f7-4eb5-9400-4f46789a2750&source_detail=WPH12%2F01+January+2022) | | [**WPH12/01** October 2021 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2021-october-wph12-01/#q-11) | **Q11** Gemstone Refraction and Internal Reflection - Edexcel IAL Physics Oct 2021 Q11 | FRQ | 2 of 3 parts ((a), (b)(i)) | 7 of 9 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=a6a4d67e-15cf-4c88-8068-dbcf14bb868f&question_id=fc6107a8-1305-47d2-8897-6f983d2d7636&source_detail=WPH12%2F01+October+2021) | | [**WPH12/01** June 2021 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2021-june-wph12-01/#q-13) | **Q13** Refraction and Total Internal Reflection in Glass - Edexcel IAL Physics June 2021 Q13 | FRQ | 1 of 2 parts ((a)) | 5 of 9 on the paper | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=1edbe5c1-050a-47b1-b2d3-6cb7932da279&question_id=065fd832-8027-4320-9a94-bc2d3392f290&source_detail=WPH12%2F01+June+2021) | | [**WPH12/01** January 2021 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2021-january-wph12-01/#q-15) | **Q15** Refraction of Light in a Cup - Edexcel IAL Physics Jan 2021 Q15 | FRQ | 2 parts ((a), (b)) | 5 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=0685a005-c20b-4099-9db0-869cf6f6e4cf&question_id=ec8668c3-7122-4a7c-8f48-1090ca3280a5&source_detail=WPH12%2F01+January+2021) | | [**WPH12/01** October 2020 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2020-october-wph12-01/#q-11) | **Q11** Snell's Law and Critical Angle - Edexcel IAL Physics Oct 2020 Q11 | FRQ | 1 of 2 parts ((a)) | 2 of 4 on the paper | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=30b9f85f-384f-48e3-b52d-af344e695501&question_id=6ba541ad-7876-4a46-a844-84ea4280a8a8&source_detail=WPH12%2F01+October+2020) | | [**WPH12/01** October 2020 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2020-october-wph12-01/#q-16) | **Q16** Sound Propagation in Sea Water - Edexcel IAL Physics Oct 2020 Q16 | FRQ | 1 of 3 parts ((a)) | 5 of 9 on the paper | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=30b9f85f-384f-48e3-b52d-af344e695501&question_id=711f563b-e4b6-4857-8af9-d056b4e96b3b&source_detail=WPH12%2F01+October+2020) | | [**WPH12/01** January 2020 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2020-january-wph12-01/#q-8) | **Q8** Refraction of Transverse and Longitudinal Waves - Edexcel IAL Physics Jan 2020 Q8 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=68c06fc7-b8d0-47b8-8712-5b4ad068842c&question_id=a673c4e1-d0cd-411a-919a-11b3977a5077&source_detail=WPH12%2F01+January+2020) | | [**WPH12/01** January 2020 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2020-january-wph12-01/#q-15) | **Q15** Water Wave Refraction and Calculations - Edexcel IAL Physics Jan 2020 Q15 | FRQ | 2 of 3 parts ((a), (b)(i)) | 7 of 10 on the paper | Hard | [Go to Practice Hub](https://www.examsci.com/practice?set_id=68c06fc7-b8d0-47b8-8712-5b4ad068842c&question_id=f767d7e6-4418-47aa-bdbd-e8fb6d7a3ee3&source_detail=WPH12%2F01+January+2020) | | [**WPH12/01** October 2019 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2019-october-wph12-01/#q-3) | **Q3** Refractive Index of Water - Edexcel IAL Physics Oct 2019 Q3 | MCQ | MCQ · 1 part | 1 | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=169c81d3-9078-4e0c-8ece-200d01be50e5&question_id=ce4827f5-86b3-4683-8dcb-e78bfdb622fc&source_detail=WPH12%2F01+October+2019) | | [**WPH12/01** October 2019 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2019-october-wph12-01/#q-18) | **Q18** Light Polarisation and the Brewster Angle - Edexcel IAL Physics Oct 2019 Q18 | FRQ | 3 of 5 parts ((c)(i), (c)(ii), (c)(iii)) | 7 of 11 on the paper | Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=169c81d3-9078-4e0c-8ece-200d01be50e5&question_id=ef9f7afa-f080-4f14-830c-e582349ff64d&source_detail=WPH12%2F01+October+2019) | | [**WPH12/01** June 2019 · Edexcel IAL](https://www.examsci.com/past-papers/edexcel-ial/physics/physics-unit-2-wph12/2019-june-wph12-01/#q-18) | **Q18** Refraction and Total Internal Reflection in Endoscopes - Edexcel IAL Physics May 2019 Q18 | FRQ | 2 of 3 parts ((b), (c)) | 6 of 8 on the paper | Easy | [Go to Practice Hub](https://www.examsci.com/practice?set_id=ac1ff5b2-f21b-4af1-906c-a87572cb18c1&question_id=af0ed148-43fe-428d-b0db-25176f5aba25&source_detail=WPH12%2F01+June+2019) | ## Related topic questions in Waves and Particle Nature of Light - [33 understand the terms amplitude, frequency, period, speed and wavelength](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/33-understand-the-terms-amplitude-frequency-period-speed-and-wavelength/) — 21 question items · 14 papers — 37 marks · 2019–2026 - [34 be able to use the wave equation $v=f\lambda$](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/34-be-able-to-use-the-wave-equation-v-f-lambda/) — 36 question items · 19 papers — 117 marks · 2019–2026 - [35 be able to describe longitudinal waves in terms of pressure variation and the displacement of molecules](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/35-be-able-to-describe-longitudinal-waves-in-terms-of-pressure-variation-and-the/) — 10 question items · 9 papers — 15 marks · 2019–2026 - [36 be able to describe transverse waves](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/36-be-able-to-describe-transverse-waves/) — 11 question items · 10 papers — 20 marks · 2019–2026 - 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Other parts of the same questions are assessed under different statements and are excluded from this page. **Which papers include this subtopic?** The table lists every matching session from 2019–2026. Each row links to the question anchor on the paper page, where the full paper context and practice entry point are available. **Why can one question appear under several subtopics?** The parts of one question can assess different syllabus statements. Each part is counted under its own subtopics, so the same question stem can appear on several subtopic pages while each page lists only the parts and marks tagged to that statement. **Can I practise these questions with AI marking?** Yes. Open a paper from the table and use the Interactive Practice Hub entry point. The page itself is static HTML so search engines and retrieval agents can read the full question list without executing JavaScript. --- Full page with native tables, bar charts and Practice Hub links: https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-2-wph12/waves-and-particle-nature-of-light/45-know-and-understand-that-at-the-interface-between-medium-1-and-medium-2-n-1-sin/