Question

QUESTION If the water is replaced by a transparent fluid with a higher index of refraction, the critical angle of the fluid- air boundary is: O smaller. o the same as for water. o larger PRACTICE IT Use the worked example above to help you solve this problem. (a) Find the critical angle for a water-air boundary if the index of refraction of water is 1.33. (b) Use the result of part (a) to predict what a fish will see (see figure in example) if it looks up toward the water surface at angles of 43.8°, at the critical angle, and at 59.8° 43.80 P & Direction IA beam of light shone toward the surface will be completely reflected down toward the bottom of the pool. Reversing the path, the fish sees a reflection of some object on the bottom. Direction II A beam of light from underwater will be refracted at the surface and enter the air above. Because the path of a light ray is reversible (Snell's law works both going and coming), light from above can follow the same path and be perceived by the fish. III A beam of light will travel through the air- water boundary without changing direction. The fish will see the object exactly as it would in the air. IV Light from underwater is bent so that it travels along the surface. This means that light following the same path in reverse can reach the fish only by skimming along the water surface before being refracted towards the fish's eye. EXERCISE HINTS: GETTING STARTEDI IM STUCK! Suppose a layer of oil with n = 1.53 coats the surface of the water. What is the critical angle for total internal reflection for light traveling in the oil layer and encountering the oil-water boundary? = !

Answer 1

Solna Critical angle at the air-water boundary - Oc= sint (7,33) = 48.60] 6 at temperature 43.8" option il is applicable at Oception in is applicable at 59.8" option Ius applicable c) ginen n = 1.53 then Oc= sin" ( 133 ) = [Oc= 60.370) Now if the water is replaced by a transparent fluid with a higher index of refaction, the critical angle of the fluid air boundary is smaller