FOOTE : TEMPERATURE AND EMISSIV1TY 



321 



(6) 



0.1492 322 



A = 0.304 e x e? 



Where X = wave length in microns and T = true absolute 

 temperature. The relation between the color temperature and 

 true temperature follows from equation (3) viz. 1/T' = 1/T — 

 0.0000104. The agreement between the computed and observed 

 values illustrated in the following table is surprisingly good, 

 and proves at once that the above theoretical relations have a 

 sound physical significance. 



TABLE II 



As seen from columns 6 and 7, the color temperature, computed 

 by equation (3) where p = 0.0000104, agrees far within experi- 

 mental errors with the observed color temperature, the difference 

 between the computed and observed values showing an average 

 deviation of only 5°. 



Using equation (6) one can predict what the emissivity at any 

 wave length will be. Table III gives the emissivity of tungsten 

 for several wave lengths. Whether equation (6), obtained indi- 

 rectly from the color temperatures, can be used as far out as 

 X = 0A/x is of course questionable. It is not likely however 

 that the values are in great error. 



