O Level Physics | Light | Lesson 3 | 2025 | Physics by TPS

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3 Waves
3.2 Light

3.2.2 Refraction of light
1 Define and use the terms normal, angle of incidence and angle of refraction
2 Define refractive index n as n = sin i/sin r ; recall and use this equation
3 Describe an experiment to show refraction of light by transparent blocks of different shapes
4 Define the terms critical angle and total internal reflection; recall and use the equation
n =1/sin c
5 Describe experiments to show internal reflection and total internal reflection
6 Describe the use of optical fibres, particularly in telecommunications, stating the advantages of their use in each context

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3.2.3 Thin lenses
1 Describe the action of thin converging and thin diverging lenses on a parallel beam of light
2 Define and use the terms focal length, principal axis and principal focus (focal point)
3 Draw ray diagrams to illustrate the formation of real and virtual images of an object by a converging lens and know that a real image is formed by converging rays and a virtual image is formed by diverging rays
4 Define linear magnification as the ratio of image length to object length; recall and use the equation linear magnification = image length/object length
5 Describe the use of a single lens as a magnifying glass
6 Draw ray diagrams to show the formation of images in the normal eye, a short-sighted eye and a long-sighted eye
7 Describe the use of converging and diverging lenses to correct long-sightedness and short-sightedness