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Why a Straw Looks Bent in Water

Part of Reflection & Refraction · GCSE GCSE Physics revision

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.

Topic position

Section 1 of 13

Practice

15 questions

Recall

15 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!

Keep building this topic

Read this section alongside the surrounding pages in Reflection & Refraction. That gives you the full topic sequence instead of a single isolated revision point.

Reflection — The Law of ReflectionRefraction — Bending at BoundariesWhy Refraction Happens

Practice Questions for Reflection & Refraction

According to the law of reflection, the angle of incidence is:

  • A. Always 90 degrees
  • B. Greater than the angle of reflection
  • C. Equal to the angle of reflection
  • D. Measured from the reflecting surface
1 markfoundation

Explain why a ray of light bends when it passes from air into water.

3 marksstandard

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)

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Reflection — The Law of Reflection