MICROSCOPY 



87 



Real image 



Eyepiece 



image 



Virtual image 



Fig. 8-3. Image formation in the compound micro- 

 scope. 



any one medium it moves with constant speed, but the speed is different 

 in a different material. Any point on a moving beam can be pictured as 

 a new^ source of hght from which new beams spread. The vibration 

 occurs in all the planes perpendicular to the direction of movement. 

 These statements will be elaborated in the following sections. 



Visible light is but a small part of a much broader spectrum of elec- 

 tromagnetic energy. We commonly think of this electromagnetic energy 



