1. G.K.BHARAD INSTITUTE OF ENGINEERING Prepared by: AKABARI VIRAL M. 130590107002 Sub : PHYSICS Sub code: 2110011 Total internal reflection

3. The picture shows the image of a boy formed by a glass. The glass surface is not smooth enough. Only very small amount of light is reflected by the glass. The environment outside is not dark enough. Light ray should undergo refraction instead of reflection. dim image

4. The inside surface of water or a glass block can act like a mirror.

5. A light ray hits the inside face of a semicircular block as follows. What will happen? air glass

6. The incident ray splits into 2 rays. angle of refraction < 90 o incident ray reflected ray refracted ray air glass For a small angle of incidence

7. incident ray reflected ray air glass CC as angle of incidence , angle of refraction  eventually, angle of refraction = 90  refracted ray angle of incidence = critical angle C

8. no refracted ray reflected ray air glass angle of incidence continues to , incident ray

9. Therefore, if angle of incidence > C, the light ray is totally reflected inside. reflected ray air glass incident ray This is called total internal reflection.

10. incident ray reflected ray air glass C C refracted ray sin 90 o sin C n = 1 sin C  n = C = sin  1 or 1 n ()

11. critical angles of different materials Medium Refractive index Critical angle 1.50–1.70 30  –42  Glass Water Perspex Diamond 1.33 49  1.5 42  2.42 24 

12. aPrisms in optical instruments plane mirror = glass + silvered surface glass sheet silvered surface forms the image

13. I 1 I 2 I 3 O object multiple reflection inside the glass multiple images formed nuisance in optical instruments

14. 45  If light rays strike the inside face at an angle > 42 , glass prism behaves like a perfect mirror. 45 

15. Prisms are used as mirrors in periscopes and binoculars.

16. In single-lens reflex camera A five-sided ‘pentaprism’ reflects light from the mirror into the eye. film mirror

17. bMirage On a dry road. In a desert.

18. Hurray! On a hot day, you may see a pool of water at a distance in a desert. Sorry! What you see is just a MIRAGE.

19. It happens due to total internal reflections. layers of air near the ground – hot – less dense than upper air – lower refractive indices Image of the sky

20. light refracted more and more towards the horizontal Image of the sky

21. When light meets a layer of air near the ground at an angle greater than C, Total internal reflections occurs. Image of the sky

22. cLight guides Light can pass through a curved perspex rod! The rays bounce inside the rod. None of them is lost to the air from the sides.

23. Applications 2 as a ‘light guide’ for the doctor to see inside the human body 1 optical fibre cable made up of a bundle of glass fibres glass fibre bundle of fibres