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U10 Cn1 Refraction Intro


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Introduction to refraction

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U10 Cn1 Refraction Intro

  1. 1. Refraction of light E. Alexander Burt Unit 11 lesson 1
  2. 2. Refraction is bending of light rays <ul><li>Refraction occurs at a boundary </li></ul><ul><ul><li>The speed of light must change at the boundary </li></ul></ul><ul><ul><li>The angle of the light ray is measured from the normal, as was the case with reflection </li></ul></ul><ul><ul><li>If the speed slows across the boundary, the refracted angle will be smaller – the light ray will bend toward the normal. </li></ul></ul><ul><ul><li>If the speed increases across the boundary, the light ray will bend away from the normal. </li></ul></ul>
  3. 3. Refraction, illustrated.
  4. 4. Refraction may combine with reflection.
  5. 5. Index of Refraction <ul><li>To calculate the exact angle of refraction, we need to know the index of refraction “n” </li></ul><ul><li>The index of refraction is the speed of light in a vacuum (c) divided by the speed of light in “stuff” (v) </li></ul>
  6. 6. Index of Refraction, 2 <ul><li>The higher the index of refraction, the more the speed of light changes, and the more the light ray will bend. </li></ul><ul><li>Typical indices of refraction are in the range of 1 – 2.5 </li></ul>
  7. 7. Snell’s Law <ul><li>Snell’s law allows us to calculate the angle of the refracted light ray if we know the angle of the incident light ray and the indices of refraction. </li></ul>