Laser light — UPSC Physics Optional CSE 2020 Paper I

For free space show that electromagnetic (EM) wave is transverse in nature. Show that for free space, the total outward flux of EM energy through surface S bounding volume V is equal to the rate of loss of EM energy from the volume V. A laser beam of 2\ \mathrm{mm} diameter has average power of 20\ \mathrm{GW}. Calculate the peak values of electric and magnetic fields in the laser beam.