Consider an electromagnetic wave travelling in vacuum, where the electric field is given by: E(r, t) = 40(V/m) sin[(8 x 105 rad/m) (x + ct) + 1.57 rad] 9 a) Compute the: i. frequency ii. wavelength 111. period iv. amplitude v. phase velocity vi. direction of motion b) Write the corresponding expression for the magnetic field of this travelling wave (don't forget to include the proper units and direction). c) Plot this waveform as a function of x at time t=0