

|  
         | 
    
|  
         | 
    
| 
         refracted 
          light 
       | 
    
|  
          
          flat surface where n1<n2 
       | 
    
|  
          
          spherical surface 
          where n1<n2 
       | 
    
|  
         | 
    




|  
          
          spherical surface where n2< 
          n1 
       |