258 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1954 



p Resistivity of material 



R Resistance 



S Coil volume 



V Ratio of flux attained at time t to steady state flux 



W Power; I'R 



MAGNETIC : 



A Equivalent pole face area 



J. 2 Effective pole face area (design value) 



B Induction (flux density) 



B' Value of B for maximum permeability 



B" Saturation density 



Bm Density at m = 1000 



Br Remanence (density at i/ = 0) 



^ (Ro 4" (Rl 



(Ro 



F Magnetic pull 



S? Magnetomotive force; -Itt^V/ 



CFc Coercive magnetomotive force 



H Field intensity 



He Coercive force 



L Inductance 



H Permeability 



Ha Permeability of air 



h' Maximum value of permeability 



(R Reluctance 



(Re Reluctance of the core 



(Re Minimum value of core reluctance 



(Ri (R(x) for X ^ Xi 



(Rj Initial incremental reluctance 



(Ro Equivalent closed gap reluctance 



(Rz, Equivalent leakage reluctance 



(Rlo Effective leakage reluctance (design value) 



(Ro2 Effective closed gap reluctance (design value) 



(Rl f (Ro + J 



6i(x) Equivalent relay reluctance ^^ 



(Ro + (Rl + I 



(p flux 



$ Steady state flux 



