This deep dive covers Why Refraction Happens 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 4 of 13 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
💡 Why Refraction Happens
Refraction occurs because different media have different optical densities, which affects how fast light (or any wave) can travel through them. When a wave front hits a boundary at an angle, one side of the wave hits the new medium first and slows down, while the other side is still in the old medium at its original speed. This causes the wave front to rotate — bending the direction of travel.
A helpful analogy: imagine a marching band moving across a field and hitting a patch of mud at an angle. The first soldiers to enter the mud slow down; the others are still on grass and moving fast. The whole row of soldiers pivots — this is exactly what happens to light at a glass surface.
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.