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Physics vocabulary · Light and Optics

Refraction

Meaning in physics, with examples

/rɪˈfrækʃən/nounCore term

In physics, refraction means: The change in direction of a wave as it passes from one material into another, caused by a change in its speed. It is why a straw looks bent in a glass of water.

In Turkish: kırılma, ışığın kırılması

How it is used

Described by Snell's law, n₁ sin θ₁ = n₂ sin θ₂, where n is the refractive index. Light bends towards the normal when it slows down (air to glass) and away from the normal when it speeds up. Lenses and rainbows depend on refraction.

Example sentences

  1. Refraction makes the pool look shallower than it really is.

  2. Measure the angle of refraction for five different angles of incidence.

Common collocations

  • angle of refraction
  • refractive index
  • Snell's law
  • refraction of light
  • reflectionThe bouncing back of light, sound or another wave when it hits a surface. For a flat mirror, the angle of reflection equals the angle of incidence.
  • lensA curved piece of glass or plastic that bends light by refraction to form an image. A converging lens brings light rays together; a diverging lens spreads them out.
  • total internal reflectionThe complete reflection of light back into an optically denser material, such as glass or water, when it meets the boundary at an angle greater than the critical angle.
  • wavelengthThe distance between two neighbouring points on a wave that are at the same stage of their cycle, such as two crests. It is shown by the Greek letter lambda (λ).
  • focal lengthThe distance from the centre of a lens or mirror to its focal point, where parallel rays of light meet or appear to come from. It is usually given in centimetres or metres.

More terms: Light and Optics

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