2. Network variables(网络变量) The systems of units( M.KSsystem)(单位制) Length [meter(m) Mass [kilogram(kg) Time second(s) Current--i(,I ----(A, mA,HAo) The net time-rate of transference(I*ie)of charge is referred to as the flow of current q(t)= i(r)dt at (2) Energy(or work)-w()2. Network variables (网络变量) The systems of units (M.K.S.system) (单位制) Length [meter] (m) Mass [kilogram] (kg) Time [second] (s) (1) Current--i(t), I ---- (A,mA,μA...) The net time-rate of transference (传递) of charge is referred to as the flow of current. − = = t q t i d dt dq i(t) ( ) ( )  (2) Energy (or work)--w(t) (J)