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10 2-refractionna-111113040434-phpapp02
- 1. WELCOME
- 2. KERALA UNIVERSITY COLLEGE OF TEACHER EDUCATION,KOLLAM
- 4. LIGHT •What is Refraction? •What is Optical Density? •The Laws of Refraction •The Refractive index •Angle of Incidence / Refraction •Total Internal Reflection
- 5. LIGHT Refraction is the change in direction of light when it passes from one medium to another.
- 6. LIGHT If light ray enters another medium perpendicular to boundary, the ray does not bend.
- 7. LIGHT When the light ray travels from air to water, the refracted ray bends towards the normal. i r air water Incident ray Refracted ray normal i – angle of incidence r– angle of refraction
- 8. LIGHT When the light ray travels from water to air, the refracted ray bends away from the normal. i r air water Incident ray Refracted ray normal i – angle of incidence r– angle of refraction
- 9. LIGHT During refraction, light bends first on passing from air to glass and again on passing from the glass to the air.
- 10. LIGHT During refraction, light bends first on passing from air to glass and again on passing from the glass to the air. i r Incident ray Emergent ray Refracted ray Reflected ray air air glass
- 11. LIGHT Light slows down when it enters an optically denser medium. The refracted ray bends towards the normal when the second medium is optically more dense than the first. i r air water Incident ray Refracted ray normal
- 12. LIGHT Light speeds up when it enters an optically less dense medium. The refracted ray bends away from the normal when the second medium is optically less dense than the first. air water i r Incident ray Refracted ray normal
- 13. LIGHT Among the 3 transparent mediums (air, water and glass), glass has the highest optical density. air water i1 r1 Incident ray Refracted ray glass i2 r2 Refracted ray air water i1 r1 Incident ray glass i2 r2 Refracted ray Refracted ray
- 14. LIGHT Take a look at this...
- 15. LIGHT The critical angle is the angle of incidence in the optically denser medium for which the angle of refraction is 90o . When i = critical angle,c r = 90o .
- 16. LIGHT This is called TOTAL INTERNAL REFLECTION. When i > critical angle, the ray gets reflected internally.
- 17. LIGHT For TOTAL INTERNAL REFLECTION to take place: The light ray must travel from an optically denser medium towards a less dense one. The angle of incidence must be greater than the critical angle. Direction of light path i
- 18. LIGHT How do we calculate the critical angle? We know that r = 90o …
- 19. LIGHT Total Internal Reflection in Prisms
- 20. LIGHT Total Internal Reflection in Prisms
- 22. THANKYOU