Effect caused hy Incident and Emergent Light. 



861 



to the incident effect plotted against log B 2 /A will be identical 

 in form with that plotted against thickness. 



.030 .£0 .150 .150 .ZI0 .Z.40 -110 30 

 LOGARITHM B,/ A ^ THICKNESS- 



It is seen that all the curves possess a common form, such 

 that, as the metal decreases in thickness the emergent beam 

 gradually becomes more prominent in its effect, until a 

 certain thickness is reached where the ratio of the emergent 

 to the incident effect attains a constant value. To this con- 

 stant value must be added the absorption due to the millimetre 



Fig. 5. 



ucvQG fof Absorption 



b^ Qua<t;'- - 



J 02. /.Ok HO //4 



emerged! effect. 



Ufa 1.3 



quartz plate upon v^hich the metal films are mounted. Th< 

 corrected values thus obtained * are given in fig. 5. 

 * Fur method and data &ee pt. i. he. cil. p. 338. 



