CHAPTER 14 REFRACTION air (rarer medium) transparent circle TIR C depth C TIR
C C diver FIG. 14.22 Calculating the area of Snell’s window QUESTIONS AND ANSWERS H
8. A diver 4 m underwater looks up and notices a circle of transparent light on the water surface. Given the refractive index of the water is 1.38, calculate the area of light that the diver sees.
Solution radius 4 m 46.4° FIG. 14.23 You may now complete Exercise 14D (page 152). CHAPTER 14 EXERCISE 14A
1. A student is doing an experiment to measure the refractive index of various materials. He uses an acrylic block and gets an angle of incidence of 54° and angle of refraction of 33°. Find the block’s refractive index. He then tries glass of refractive index 1.5. The angle of refraction in this case is 25°. What was the angle of incidence?
2. Draw a diagram showing the full path of light as it enters a block of glass (n = 1.5) at an angle of incidence of 25°.
3. State the laws of refraction of light.
4. A light ray enters glass from air. It has an angle of incidence of 72° and an angle of refraction of 33°. Calculate the refractive index of the glass.
5. If the refractive index of Pyrex is 1.47, calculate the refractive index between Pyrex and air.
LEAVING CERTIFICATE PHYSICS 151
The radius of the transparent circle of light can be found using trigonometry (Fig. 14.23).
