Piimary and Secondary 7 Rays. 927 



The different radiators are supported by string. 

 No radiator X = *71 



5 cms. of carbon \—'6S 

 10 cms. of carbon X = *65 

 2 cms. of iron X = *G5 

 5 cms. of iron X = *59 

 •416 cm. of lead X, = '625 



The area of the radiator is constant (11 x 11) cm. Each 

 radiator has had, therefore, a hardening effect. It will be 

 shown later that the relative values of these absorption coeffi- 

 cients remain the same for each position of the electroscope. 

 Consider now the amount which passes through these 

 radiators. In fig. 2 are plotted the curves showing the 



scnle-div./min. FiV 



34 



Th/c/c//£ss x D£/rs/ry 

 Group A shows absorption of the direct 7 rays through different 

 thicknesses of three radiators. Side of electroscope is 6 mm. thick, 

 ^roup B, side of electroscope is 12 mm. thick. 



