Chapter 9 · Physics
Light: Chapter Introduction
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We see things because light bounces off them into our eyes. At a surface light has 2 options: bounce back (reflection) or go in and bend (refraction).
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Light Travels in Straight LinesYou can hear a friend round a corner but not see them: sound bends, light travels in straight lines. We draw its path as a ray.Physics
Key points
- We see non-luminous objects by the light they reflect into our eyes.
- Reflection: light returns into the same medium (mirrors).
- Refraction: light bends on entering another medium because its speed changes (lenses).
- Part 1: mirrors + reflection; Part 2: refraction + lenses. Your eye has a lens too.
Two options at a surface
| Behaviour | What happens | Example |
|---|---|---|
| Reflection | Light returns into the same medium | Mirror; image in a spoon |
| Refraction | Light bends as its speed changes | Pencil in water looks broken; lenses |
What the chapter covers
- Part 1: laws of reflection, plane and spherical mirrors, image formation, mirror formula.
- Part 2: laws of refraction, refractive index, lenses, lens formula, power of a lens.
Quick quiz
4 questions. Choose an answer for each, then submit to see your score and the explanations.
More from Light – Reflection and Refraction
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