Refraction

• 1. John Parkinson 1

2. John Parkinson 2 I think we are being watched! Refraction is the Bending of Waves due to a Change in Velocity Refraction is the Bending of Waves due to a Change in Velocity I wasnt going to jump anyway 3. John Parkinson 3 air glass / water REFRACTION 4. John Parkinson 4 1 2 normal 1 1 = angle of incidence Refracted ray2 2 = angle of refraction Incident ray 5. John Parkinson 5 Opticallyless dense medium (1) Optically denser medium (2) Waves travel SLOWER Wavelength REDUCED Frequency UNCHANGED 6. John Parkinson 6 Incident ray normal Refracted ray 1 2 1 2 2 1 21 sin sin nSNELLs LAW 7. John Parkinson 7 THE MIRAGE Hot Desert Sand air layers Air layers closer to the sand are hotter and less dense. Light from the sky is successively bent until a critical angle is reached and then total internal reflection occurs. A mirage "water" illusion is seen because the mind initially interprets the light rays reaching our eyes as having come along a straight path originating from the ground. Thus, the image of that patch of sky we see "on the ground" is interpreted as a surface "pool of water." Water for my hump! 8. Choose the letter of the correct answer. 1. An incident ray travels from air to water as shown. Which is the refracted ray? a. R1 b. R2 c. R3 d. R4 R1 R2 R3 R4 9. 2. When light beam emerges from water to air the speed of light a. increases b. decreases c. remains the same d. becomes zero 10. 3. A spear fisher at A sees a fish which appears to be at N. Where should the fisher aim so as to hit the fish? a. at O c. at N b. at M d. none of these A. M. N . O. 11. 4. A ray of light passes from a transparent substance to another. What happens to its speed if it is from air to water? a. slows down and changes its direction of travel b. speeds up and changes its direction of travel c. decreases but travel straight d. remains the same 12. 5. Which property of light is shown when pencil partly immersed in water appears bent? a. interference b. diffraction c. reflection d. refraction 13. Assignment What determines how large the bending of light ray is when it passes through different medium?