1. P5g - Refraction of waves Refraction is…

2. Refraction

7. Refractive index (n) n = speed of light in a vacuum speed of light in the medium Q ~ What is n for a) air b) water 225 000 000 Water 299 900 000 Air 300 000 000 Vacuum Speed of light (m/s) Medium

8. Snell’s law i r n = sin i sin r medium i medium r “ Angle of refraction depends on the refractive index”

9. Snell’s law n = sin i sin r Q ~ If the medium is water (n = 1.33) and angle i is 30  , what is angle r ? r = 22  n = sin i sin r 1.33 = sin 30 sin r sin r = sin 30 1.33 sin r = 0.5 = 0.38 1.33

10. Snell’s law n = sin i sin r Q ~ In another medium, if i is 30  and r is 12  , what is n? Q ~ If the medium is water (n = 1.33) and angle i is 40  , what is angle r ?

12. Refractive index between 2 media i r medium i medium r n = n r n i

13. Refractive index between 2 media i r water (n = 1.33) air (n = 1.0) = 0.75 n = n r n i n = n air = 1.0 n water 1.33

14. Refractive index between 2 media i r water (n = 1.33) glass (n = 1.5) = 1.12 n = n r n i n = n glass = 1.5 n water 1.33

16. Refraction investigation i r air (n = 1.0) glass (n = ?) n = n r n i n glass = ? n = n glass = n glass n air 1.0

17. Refraction investigation i r air (n = 1.0) perspex (n = ?) n = n r n i n perspex = ? n = n perspex = n perpex n air 1.0

18. Refractive index and critical angle “ Total internal reflection”

19. Refractive index and critical angle n = n r n i = sin i sin r = sin c sin 90 n r n i = sin c n r n i sin 90 = 1