Investigate reflection and refraction
Use a ray box or narrow beam, mark the incident and refracted rays, draw the normal and measure angles. Keep the block shape and ray position controlled when comparing angles.
GCSE Physics resources
AQA GCSE Waves
Light Required Practical
Use a ray box or narrow beam, mark the incident and refracted rays, draw the normal and measure angles. Keep the block shape and ray position controlled when comparing angles.
Start here
The quick revision snapshot
Use a ray box or narrow beam, mark the incident and refracted rays, draw the normal and measure angles. Keep the block shape and ray position controlled when comparing angles.
By the end, you should be able to…
- Explain investigate reflection and refraction using precise physics language.
- Apply the relevant equations, diagrams or practical method to an exam-style situation.
- Use the mini quizzes and practice answers to identify and correct a misconception.
Core learning content
Learn the idea before you practise it
Start with this short teaching sequence for Light Required Practical. Read the model, use the visual, then test your recall before moving into examples and exam practice.
Build the picture
Angles of incidence, reflection and refraction are measured from the normal, not the surface. Mark the ray positions with small crosses before removing the block so the line can be drawn accurately. A narrow ray and careful protractor reading reduce uncertainty.
Use the right relationship
Choose a relationship because of the physical change in the question, not because it is familiar. Wave speed: v = fλ (m/s, Hz, m). Period: T = 1 ÷ f (s, Hz). Magnification: magnification = image height ÷ object height (no unit). Keep the unit next to each value while you substitute.
What a strong answer does
Show the normal, identify the measured angle, repeat readings and explain how ray thickness and protractor resolution affect uncertainty. Before writing, underline the command word and identify the information that matters. Keep a calculation as equation, substitution and answer with unit; keep an explanation as a linked chain using because, so or therefore. Finish by checking that the final sentence answers the exact context in the question and that the number, direction or conclusion agrees with the evidence given.
Retrieval practice
Quick checks
Answer without looking back first. The feedback explains the model, so a wrong answer still helps you learn.
Mini quiz 1
Check the core idea
Mini quiz 2
Apply the model
Mini quiz 3
Use exam precision
Try it
Light practical angle tester
How can a normal line make reflection and refraction angles measurable?
What to notice: the readout and written explanation remain available if you do not use the controls.
Worked examples
See the method being built
Cover the answer, attempt the method and then compare your physics language as well as the number.
Example 1 · Reflection result
Incident angle is 42° to normal. Predict reflected angle.
- Use law of reflection.
- Angles from normal.
- State degrees.
Show the answer
Reflected angle = 42°.
Example 2 · Refraction method
Describe how to measure refraction through a glass block.
- Trace block, mark incident/refracted rays.
- Remove block and draw rays/normal.
- Measure from normal.
Show the answer
Use a narrow ray, mark positions, draw normal at boundary and measure angles with a protractor.
Example 3 · Uncertainty
A wide ray makes angle reading difficult. Improve.
- Identify broad ray as uncertainty.
- Narrow beam/slit.
- Use fine pencil marks.
Show the answer
Use a narrow ray box slit and thin pencil lines to reduce angular uncertainty.
Misconception clinic
Common wrong turns
Each of these is tempting because it sounds almost right. Replace it with the precise physics before you meet it in a question.
- Measuring from the block surface.
- Leaving the block in place when drawing internal rays without markers.
- Using a broad unmarked beam.
Independent practice
Exam-style questions
Use the working space first. Reveal the guidance only after you have committed to an answer, then improve the exact part that would gain the next mark.
1. State what the normal is.
[1 mark]Show answer and marking guidance
A line perpendicular to the surface at the point where the ray meets it.
2. State the law of reflection.
[1 mark]Show answer and marking guidance
Angle of incidence equals angle of reflection.
3. Why measure angles from the normal?
[2 marks]Show answer and marking guidance
The laws of reflection/refraction define angles relative to the normal.
4. Give one control variable in a glass-block refraction investigation.
[1 mark]Show answer and marking guidance
Use same block/material and same ray position/colour.
5. State why crosses are marked on ray paths.
[1 mark]Show answer and marking guidance
They allow accurate rays to be drawn after the block is removed.
6. Give one way to improve reliability.
[1 mark]Show answer and marking guidance
Repeat for each incident angle and compare/average readings.
Questions pupils ask
GCSE Physics FAQs
What is the key idea in Light Required Practical?
A wave transfers energy without transferring matter overall. Use diagrams to keep amplitude, wavelength, frequency, speed and direction distinct.
How should I practise Light Required Practical?
Read the snapshot, attempt the worked examples without looking, complete the mini quizzes and then use the practice questions to check your wording and method.
Next step
Keep your revision moving
Physics sticks when you move between explanation, retrieval and application.