a. Write an expression for the electric field vector of a uniform plane wave in free space that is propagating in the direction given by a line from the origin to the point (3,0,4) and that is linearly polarized along the y-direction. It has a wavelength of 2 µm and reaches its positive maximum amplitude of 20 V/m at a distance of 1 m from the origin at t = 0 s.
b. Compute the irradiance of this wave.