THEORY OF MULT I -ELECT RODE VACUUM TUBE CIRCUITS 669 



The physical interpretation of equations (7) to (9) is readily ob- 

 tained. It follows from (7) that the equivalent circuit of Fig. 1 for 

 first order quantities is given by Fig. 2. The equivalent circuit of 



^9- 



'g-p, 



Fig. 2 — Equivalent circuit — first-order effects. 



Fig. 1 for second and third order effects are those shown in Fig. 3, 

 and Fig. 4, respectively. 



(•^zo^pi* b,.«p.«g.-^bo2^g, 



""gl^^zo^pi "^ '^ii®pi®gi*'^02®gi^— ^p 



Fig. 3 — Equivalent circuit — second-order effects 



It follows from (4) and (8) that 



Tpihioepi^ + hnepiCgi + hmegi^) 



. 1 / djXp d/Xp \ , . dfXp 



= rpP^iep, + UpBg^y -^2['dEg^^'dEp) '"'' ^ Wp ^"'^"' 



rg(^2oepi^ + ^uCpiegi + ^02egi^) 



(10) 





The corresponding terms in (9) can be expressed similarly 



