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Unit 4 · 10 lessons

Light & Geometric Optics

What light is and where it comes from, how mirrors and lenses bend it into images, and how the same rules explain rainbows, fibre optics, eyeglasses and cameras.

  • 88 practice questions
  • 82 flashcards
  • 7 interactive lessons
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Lessons

  1. 1What Light Is: The Electromagnetic Spectrum and Sources of LightLight as an electromagnetic wave, the spectrum from radio to gamma rays, the wave equation for light, and the different ways objects produce light, from hot filaments to fireflies to LEDs.8 questions
  2. 2Rays, the Laws of Reflection and Plane MirrorsDrawing light as rays, measuring angles from the normal, the two laws of reflection, specular versus diffuse reflection, and why a plane mirror image is the same size, upright, as far behind the mirror as you are in front, and virtual.8 questions
  3. 3Concave and Convex Mirrors with Ray DiagramsThe parts of a curved mirror, the principal rays that make ray diagrams quick, how the image in a concave mirror changes as the object moves, and why convex mirrors always give small, upright, virtual images.Interactive8 questions
  4. 4The Mirror and Magnification EquationsTurning ray diagrams into numbers: the mirror equation, the magnification equation, and the real-is-positive sign convention that tells you whether an image is real or virtual, upright or inverted.Interactive11 questions
  5. 5Refraction, Index of Refraction and the Speed of LightWhy light bends when it crosses from one material into another, which way it bends, and how the index of refraction measures how much a material slows light down.Interactive8 questions
  6. 6Snell's LawThe exact rule that links the angles on each side of a boundary to the indices of refraction, how to use it to find an angle or an unknown index, and what happens to a ray passing through a glass block.Interactive8 questions
  7. 7Total Internal Reflection, the Critical Angle and Natural PhenomenaWhy light trying to leave glass or water at a steep angle cannot escape at all, how to calculate the critical angle, and how refraction and total internal reflection explain fibre optics, sparkling diamonds, apparent depth, mirages, shimmering and rainbows.Interactive9 questions
  8. 8Converging and Diverging Lenses with Ray DiagramsHow a curved piece of glass uses refraction to bring light together or spread it apart, the three principal rays for each kind of lens, and how the image changes as the object moves, from cameras to projectors to magnifying glasses.Interactive8 questions
  9. 9The Thin Lens Equation and MagnificationThe thin lens equation and the magnification equation for lenses, the sign convention for converging and diverging lenses, and how to use them for cameras, projectors and magnifying glasses.Interactive10 questions
  10. 10The Eye, Vision Correction and Optical DevicesHow the eye forms an image and focuses, why nearsightedness and farsightedness happen and how lenses and laser surgery correct them, and how cameras, microscopes, telescopes and binoculars combine lenses, mirrors and prisms.10 questions