Inductance of Two Parallel Wires. 265 



and in the second, 



H= -EJ.(*>)/ 1+ ^\ / / 1 W,\ 

 phb/3 \ « // \ *£ / 



The total currents are 



(56) 





(57) 



(58) 



by (52). ; 



It L is the self-induction of the system per unit 



length, tLp is the imaginary part of { , or of 



w^ W% 



T + «/s /|v 1+ ^j + v 1+ M)p (59) 



In particular, if the wires be equal and of the same 

 material, as will usually occur in practice, iL is the imaginary 

 part of 



Case 0/ a Small Frequency . 



Whenp is small, ha=pa/C is exceedingly small for a wire 

 not of excessive thickness, and may be safely ignored as in 

 the above calculation, even in its first power, and thus 



K (iha) — — \ { Y (ha) + lttJq (ha) \ 



=-(7+ -2+10K-2-) 



= — log/ia practically. . . . (61) 

 K o'('M = -;L (62) 



so that on reduction, 



(63) 



and 



-$=l/{logW-^}. • • (64) 



O = K (thc)= — log Ac, 



