Using the Geometric Properties of Three Invariants in the Wave Equation for the Intensity of an Electric Field

An equation of continuity for a fluid is derived using Euler’s Principia motus fluidorum with high-order terms of smallness containing quadratic and cubic invariants of the strain rate tensor. The wave equation for the intensity of an electric field is derived using Maxwell’s system of electrodynamics equations with allowance for quadratic and cubic invariants, which describe the generation of waves of the electric field’s intensity.