電信方程式
L C ∂ 2 V ∂ t 2 + ( L G + R C ) ∂ V ∂ t − ∂ 2 V ∂ x 2 + R G V = 0 {\displaystyle LC{\frac {\partial ^{2}V}{\partial t^{2}}}+(LG+RC){\frac {\partial V}{\partial t}}-{\frac {\partial ^{2}V}{\partial x^{2}}}+RGV=0}
L C ∂ 2 I ∂ t 2 + ( L G + R C ) ∂ I ∂ t − ∂ 2 I ∂ x 2 + R G I = 0 {\displaystyle LC{\frac {\partial ^{2}I}{\partial t^{2}}}+(LG+RC){\frac {\partial I}{\partial t}}-{\frac {\partial ^{2}I}{\partial x^{2}}}+RGI=0}
を得る。