Geometrical Optics | 10th IGCSE Physics


Jul 30 - Aug 26 (16 periods)


  • Historical perspective
  • Shadows
  • Reflection
  • Refraction
  • Total internal reflection
  • Dispersion
  • Speed of light
  • Mirrors
  • Lenses

Instructional objectives

Students should be able to:

  • Understand the cause for deifferent regions of a shadow
  • State laws of reflection and refraction
  • Analyze path of light rays and predict its future course in any given reflection/refraction situation
  • Draw ray diagrams for any given situation
  • Understand when total internal reflection occurs, and how it is used in optic fibres and reflective prisms
  • understand dispersion of light
  • devise a method to measure the speed of light
  • Understand image formation by lenses and mirrors

Teaching Process

  • Reflection, refraction and total internal reflection are analyzed using blocks of glass, mirrors, lenses and lasers.
  • All situations are analyzed using ray diagrams, drawn and derived by the students themselves.
  • Students derive their own formulae where required, instead of the teacher handing it to them.
  • Emphasis on making empirical observations, by playing around with lenses and mirrors


  • Activity on shadows formed by a point source and diffuse source, to undestand umbra and penumbra
  • Plane mirror reflection, periscope
  • refraction in glass / acrylic
  • Total internal reflection in glass
  • Image formation by lenses and mirrors

Suggested reading / References

Assignments / Evaluation

  • Assignments on derivation of certain formulae
  • Quiz on applying the learnt concepts
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