Low-Frequency Approximation of Maxwell’s Equations R, L, C, and Memristor M

Circuit theory, used extensively in low-frequency electrical engineering, is a low-frequency approximation of Maxwell’s equations. It is formulated in terms of the two-terminal circuit elements such as resistance (R), inductance (L), and capacitance (C). Fano et al. [1] discussed circuit theory as a quasistatic approximation in terms of the time-rate parameter α, which was used to expand the electromagnetic fields in power series. The classical elements R, L, and C were shown to be obtained by certain combinations of the zeroth- and first-order solutions. Chua [2] pointed out that a new circuit element M, called memristor (memory + resistor), could be proposed based on the relationship between the charge q(t) and the magnetic flux Φ_m(t). Such a two-terminal element realized recently [3] has interesting properties and applications.