4. A plane wave of frequency 900 MHz is and travelling along -y direction with the electric field amplitude of 300 V/m (in vacuum). The value of electric field is -300 V at t=0 and y=0. Choose a magnetic field direction and define the polarization. Write the wave equation of the electric and magnetic field.

4. A plane wave of frequency 900 MHz is and travelling along -y direction with the electric field amplitude of 300 V/m (in vacuum). The value of electric field is -300 V at t=0 and y=0. Choose a magnetic field direction and define the polarization. Write the wave equation of the electric and magnetic field.