APPENDIX II. 



be added independently of their phase relation. But we know that 

 the algebraic sum of the e. m. f.'s of all the elements is equal to 



~ z * io' 8 volts, 



V/2 



hence we may conclude that in a distributed winding the e. m. f. 



induced is equal to AG -r- A B CD G multiplied by e. This is, 



FIG. 53- 



however, equal to 



I 2 



Z * 10"' 



= V/2 ~ 



z * io~* volts. 



This formula differs slightly from (21) as in our graphic repre- 

 sentatfon we have assumed a sinusoidal field the lines of which are 

 cutting the winding, whereas fields with straight contours have been 

 considered in Sections 19, 20 and 108. 



If the coil covers an angle of 120 degs., (Fig. 53), the e. m. f. in- 



97 



