A SURVEY OF SELECTED SOLUTIONS TO PROBLEMS OF 

 REFRACTION AND DIFFRACTION OF LIGHT WAVES AND 

 SOUND WAVES AND THE ANALOGIES OF THESE PROBLEMS 

 TO WATER WAVES 



Abstract 



Several refraction and diffraction problems in light waves 

 and sovind waves have been selected for study in the N.Y.U. ripple 

 tank. The analogies to these problems are demonstrated by test- 

 ing plastic analogue models of the system under investigation in 

 the ripple tank. If it is assumed that the initial and boundary 

 conditions of the particular problem have been satisfied by the 

 nature of the experiment, and it is found that photographs of the 

 systems undergoing experimentation clearly demonstrate the physical 

 interpretation of the mathematical solution, then we may conclude 

 that the problem has an analogy in water waves. 



The selection of the various problems depends on the practi- 

 cability of experimentation and upon the photographic technique 

 employed. The ripple tank, mentioned above, has been designed in 

 such a manner that it propagates plane waves. Therefore, one of 

 the conditions imposed on the selection of the problem is that the 

 source be of such a nature that it propagates plane waves at a 

 finite distance from the system. A possible source is a plane in 

 three dimensions, which reduces to a line source in two dimensions. 

 Another possible sovirce is a point source originating a great 

 distance from the system, so that the waves may be considered 

 as plane waves in the region of the system. Since our problems 



