CH. V] 



MAGNIFICATION OF THE MICROSCOPE 



141 



FIG. 86. DIAGRAMS TO SHOW THAT THE SIZE OF THE REAL IMAGE OF A LENS 

 DEPENDS UPON THE DISTANCE OF THE OBJECT FROM THE PRINCIPAL Focus. 



Axis The principal optic axis extended above and below. A B, B A The 

 object and the inverted real image. /, / The principal focus above and below 

 each lens. Lc The lens. 



The object is the same size in the two cases, but the images differ, depending 

 upon the distance of the object from the principal focus, being longer the nearer 

 the object is to the focus. 



FIG. 87. DIAGRAM TO SHOW THAT THE SIZE OF THE VIRTUAL IMAGE OF A LENS 

 DEPENDS UPON THE DISTANCE OF THE OBJECT FROM THE PRINCIPAL Focus. 



A B, A B The object and the virtual image. / / The principal focus. 

 L The lens, ep The eye-point, c The single, ideal refracting plane. 



As with real images, the size of virtual image in a given lens depends upon 

 the nearness of the object to the principal focus. 



