a function of the acceleration voltage to which it is subjected and is 

 expressed as 



- f 150 



where ^ is the wavelength and V is the voltage employed to accelerate 

 the electrons. It follows from the above equation that electrons acceler- 

 ated through a potential of 60,000 volts would have a wavelength of only 

 about 0.05 A. This is a wavelength that is about 100,000 times shorter 

 than the mean wavelength of visible light (5000 A). 



Lamp 



eye 



Figure 11-9. Simplified Diagram of the Optical System of the Light (left) 

 and Electron (right) Microscope. (From Coslett, V. E., 1955. "Electron 

 Microscopy," in Oster, G. and Pollister, A. W. (Eds.), "Physical Techniques 

 in Biological Research," 1, Academic Press, New York, N. Y., Fig. 3, p. 467.) 



226 / CHAPTER 1 1 



