Reflection & Refraction
Reflection is when a wave bounces off a surface. The law of reflection states that the angle of incidence equals the angle of reflection. Refraction is when a wave changes direction as it passes from one medium to another, due to a change in its speed. The amount of refraction depends on the refractive index of the materials.
Full topic guide: the detailed syllabus page with worked examples and common mistakes lives at studyvector.co.uk/gcse/physics/waves/reflection-refraction.
Topic preview: Reflection & Refraction
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Topic explanation
Reflection is when a wave bounces off a surface. The law of reflection states that the angle of incidence equals the angle of reflection. Refraction is when a wave changes direction as it passes from one medium to another, due to a change in its speed. The amount of refraction depends on the refractive index of the materials.
Reflection & Refraction is easiest to revise when it is treated as a precise exam behaviour, not a loose note-taking category. In GCSE Physics, the goal is to recognise how the topic appears in a question, identify the command word, and decide what evidence, method, or vocabulary earns marks. StudyVector keeps this page tied to AQA · Edexcel · OCR language where coverage is available, then routes practice towards the same topic so revision moves from explanation into retrieval.
A strong revision session starts with a short recall check. Write down the rule, definition, process, or method linked to Reflection & Refraction before looking at any notes. Then answer one exam-style prompt and compare your answer with the mark-scheme logic: did you make a clear point, support it with the right step, and avoid drifting into a nearby topic? This matters because many lost marks come from almost-correct answers that do not match the expected structure.
Use this guide as the first layer: understand the topic, look at the worked examples, complete the mini quiz, then move into full practice. The full StudyVector practice loop is designed to capture whether mistakes are caused by knowledge, method, language, or timing. That distinction is important. If the error is factual, you need reteaching. If the error is method-based, you need a worked retry. If the error is wording, you need command-word calibration. That is how Reflection & Refraction becomes a controlled revision target rather than another page in a folder.
Lost marks → repair task
Why marks are usually lost here
These are the error patterns StudyVector looks for after an attempt. The goal is not a generic explanation; it is one repair move and one follow-up question.
Unit, formula, or method slip
Examiner move: Select the correct method and keep units, substitutions, signs, and rounding visible.
Repair drill: Redo the calculation or method line slowly, naming the formula before substituting values.
Missing chain of reasoning
Examiner move: Show the link between point, method, evidence, and conclusion instead of jumping to the final line.
Repair drill: Write the missing because/therefore step, then retry one isomorphic question.
Weak evidence or data reference
Examiner move: Use a precise value, quote, example, diagram feature, or syllabus term to support the claim.
Repair drill: Add one concrete reference to the answer and remove any generic sentence that does not earn a mark.
Mini quiz
Use these checks before full practice. They test topic recognition, exam technique, and whether you can connect the explanation to a marked response.
1. What should you check first when a Reflection & Refraction question appears in GCSE Physics?
- A.The command word and the exact topic focus
- B.The longest paragraph in your notes
- C.A memorised answer from a different topic
2. Which revision action gives the strongest evidence that Reflection & Refraction is improving?
- A.Rereading the explanation twice
- B.Answering a timed exam-style question and reviewing lost marks
- C.Highlighting every key phrase in the topic notes
Sample questions
Topic-specific public question previews are still being reviewed. We keep them off public pages until the topic match is safe.
Exam tips
- Read the command word carefully — "explain" needs reasons; "state" expects a short fact.
- For Reflection & Refraction, show structured working even when you are practising multiple choice — it builds accuracy under time pressure.
- Mark yourself against the mark scheme style: one clear point per mark, in logical order.
- Come back to this topic after a day or two; short spaced reviews beat one long cram.
Worked examples
Example 1
Modelled exam response
A ray of light enters a glass block from air. The angle of incidence is 30°. Will the angle of refraction be greater or smaller than 30°? Explain why. Solution: The angle of refraction will be smaller than 30°. This is because light travels more slowly in glass (a denser medium) than in air. As the wave slows down, it bends towards the normal.
Example 2
Identify the task before answering
Question type: a Reflection & Refraction prompt asks for a clear response in GCSE Physics. Step 1: underline the command word. Step 2: name the exact part of Reflection & Refraction being tested. Step 3: decide whether the mark scheme wants a definition, method, explanation, comparison, or calculation. Why it works: most weak answers fail before the content starts because they answer the topic generally rather than the exact exam task.
Example 3
Turn feedback into a repair task
Suppose your answer shows partial understanding but loses marks for precision. First, rewrite the missing mark as a short target: "I need to state the mechanism, unit, reason, or evidence explicitly." Then answer one similar question without notes. Finally, compare the second attempt with the first and check whether the same mark was recovered. Why it works: Reflection & Refraction improves faster when feedback creates a specific retry, not another passive reading session.
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Common mistakes
- Confusing reflection and refraction. Reflection is bouncing off, refraction is bending through.
- Measuring the angles of incidence and reflection from the surface instead of from the normal. The normal is a line drawn at 90° to the surface.
- Forgetting that the frequency of a wave does not change when it is refracted. Its speed and wavelength do change.
Exam board notes
Covered by all major boards (AQA, Edexcel, OCR). Ray diagrams are a common way to test these concepts.
FAQs
What is the law of reflection?
The law of reflection states that the angle of incidence is equal to the angle of reflection (i = r), and that the incident ray, the reflected ray, and the normal all lie in the same plane.
Why does a straw in a glass of water look bent?
This is due to refraction. The light rays from the part of the straw that is underwater are bent as they pass from the water into the air before reaching your eyes. This makes the straw appear to be in a different position.
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Full practice set
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