A small helium-neon laser emits red visible light with a power of 3.2 mW in a beam with a diameter of 2.5 mm.
a) what are the amplitudes of the electric and magnetic fields of the light?
b) what are the average energy densities associated with the electric field and with the magnetic field?
c) what is the total energy contained in a 1.00 m length of the beam?