Telegrapher’s equations are a set of differential equations that describe the propagation of a current and voltage wave on a transmission line. In this video I derive the Telegrapher’s equations using a circuit model of an “infinitesimally” short section of transmission line.

In this video I derive the solution to Telegrapher’s equations which consists of a forward wave and a backward wave. I also define several important parameters of transmission lines in general, namely, phase velocity and wavelength.

Another fundamental parameter of travelling waves on a transmission line (which falls right out of Telegrapher’s equations) is impedance. In this video I define the characteristic impedance for the case of a loss-less transmission line.