This exam tips covers Exam Tips within Reflection & Refraction for GCSE Physics. Revise Reflection & Refraction in Waves for GCSE Physics with 15 exam-style questions and 15 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 12 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 Exam Tips
🎯 Common Question Types:
- Complete a ray diagram with correct angles (2–3 marks)
- Explain why refraction occurs at a boundary (3 marks)
- Describe/explain total internal reflection with a named application (4 marks)
- State and explain the difference between specular and diffuse reflection (2 marks)
📝 Key Command Words:
- State: Give the law of reflection as an equation (i = r)
- Describe: What happens to the light — direction, speed, wavelength
- Explain: Give the reason — speed change causes direction change
- Draw: Show normal, measure angles correctly, use arrows on rays
⚠️ Common Mistakes to Avoid:
- Measuring angles from the surface instead of the normal
- Forgetting to draw the normal in ray diagram questions
- Saying "light bends because it enters a denser medium" — it only bends if hitting at an angle
- For TIR: forgetting to state BOTH conditions (denser medium AND angle > critical)
Quick Check: Why does a diamond sparkle more than a piece of glass of the same shape?
Diamond has a higher refractive index than glass, which means a smaller critical angle (about 25° compared to 42° for glass). This means more light inside the diamond undergoes total internal reflection and is bounced around inside, producing more sparkle, rather than being transmitted out through the sides.
Practice questions for Reflection & Refraction
According to the law of reflection, the angle of incidence is:
Explain why a ray of light bends when it passes from air into water.