152 



COEFFICIENTS OF INDUCTION. 



It is sufficient to know the values of A. x corresponding to values 

 of m less than unity. We shall greatly abridge the calculations 

 by means of the following table : 



This value of L only holds, however, for the case in which 

 the dimensions of the central section to of the coil are very small 

 in comparison with the mean radius. 



782. If instead of formula (52) we use formula (53), the co- 

 efficient of self-induction of the rectangular coil may be put in 

 the form 



L = 



with 



_ 



120 6* 



24 

 Putting as above 



I &* J I 7* 2 t> 3 C 23 



- -^ L \J I+ T*- -arc tan -4--^-^ 

 24 c 2 \ & 2 15 c b 160 



221 



1440 





we have 



6m 2 



arc tan m 



