Electromagnetic Wave Equation in Two Dimensions: E = Ey m cos(ωt - kx + φ) ay + Ex m sin(ωt - kx + φ) ax

This equation describes an electromagnetic wave in two dimensions, with electric field vectors in the y and x directions. The wave has a frequency of 'ω', a wavenumber of 'k', and a phase angle of 'φ'. The amplitudes of the electric field vectors are 'Eym' and 'Exm', respectively. The wave is propagating in the direction of decreasing x, as indicated by the negative sign in front of the kx term.