EXPERIMENT 44. THE PATH OF LIGHT THROUGH A GLASS 



PRISM 



Fasten a sheet of paper to the table as before, and place 

 a prism on the paper in such a way that one face is par- 

 allel to the edge of the paper farthest away from you. 

 With a sharp pencil trace the outline of the prism. 



Then, near the edge of the paper farthest away, stick 

 two pins upright at the points A 

 and B, as shown in the diagram. 

 Put two pins in front of the prism 

 at C and D, in such a way that 

 when you look through the prism, 

 all four pins seem to be in the same 

 straight line. 



Remove the prism and the pins 

 and draw AB and CD as before, 

 prolonging them until they meet 

 the outline of the prism at E and 

 F. Join E and F with a straight 

 line which will as before show the 

 path of the light as it passed through the glass. 



From your result, state what happens when a ray of 

 light passes through a glass prism. Does the emergent ray 

 differ in direction from the incident ray ? 

 State the law of refraction. 



FIG. 42. Refraction through 

 a chandelier prism. 



EXPERIMENT 45. APPARENT DEPTH OF A POND 



A pond appears to be more shallow than it is, and a 

 basin filled with water does not seem so deep as when 

 empty. If we put a spoon or straw in a tumbler of 



