PROBLEMS ON REFRACTIVE INDEX 



is the incident ray in air, FG the refracted ray in crown glass. Tl it- 

 angle A FE is the angle of incidence, BFG the angle of refraction. 

 Sine A F E divided by sine B F G is equal to the refractive in- 

 dex of air into crown glass, or, in other words, the absolute refractive 

 index of crown glass, p ; thus in this particular case : 



(Problem) I. : 



sin A F E 



sin 45 C 



sin B F G ' ' sin 28 



707 

 -472 



This problem, however, is not actually needed by the reader of 

 this book, for a table of 

 absolute refractive indices 

 is given in Appendix B. 



It w r ill be clear from 

 the above that when the 

 refractive index, absolute 

 or relative, of a ray from 

 any first medium is given, g~ 

 the refractive index from 

 the second to the first may 

 be found. 



Thus, the absolute re- 

 fractive index LI from air 

 into glass being given as 



O _. n 



-, find 



p. f , 



the refractive 



index from glass into air. 



(Problem) II. : 



3 

 2 



. 



3 



JTJ 



"When the absolute 

 refractive indices of any 

 two media are given, the 

 relative refractive indices 

 between the media can be 

 found. 



Thus, the absolute re- 

 fractive index LI of crown 

 glass is 1'5, and the ab- 

 solute refractive index // 



of flint glass is l - 6 ; find the relative refractive index"/ 

 to flint. 



(Problem) III. : _ / _ Ij6 _ l-QQQ 



= ^' : F5 = 



The relative refractive index LI'" from flint to crown is determined 

 by (problem) ii. : 



,,'" =- = . = -938. 

 u." 1-066 



The normakto^a plane and a curved 



from crown 



