This introduction covers Why a Straw Looks Bent in Water 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 1 of 13 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
📖 Why a Straw Looks Bent in Water
Drop a straw into a glass of water and it appears to bend at the surface. Nothing has physically bent — what changed is the speed of light. Light travels more slowly in water than in air, so when it crosses the boundary at an angle, it changes direction. This is refraction, and it explains rainbows, lenses, fibre-optic internet cables, and why swimming pools look shallower than they are. Understanding how waves change direction at boundaries is fundamental to almost all optical technology!
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.
Quick recall flashcards
Law of reflection
Angle of incidence = Angle of reflection
What is refraction?
Change in direction when light enters a different medium (due to speed change)