A laser beam has intensity 2.5 × 10¹⁴ W m^–2. Find the amplitudes of electric and magnetic fields in the beam.

Given: The intensity of laser beam =2.5 × 10¹⁴W m^-2.

We have to find the amplitudes of electric and magnetic field. The

amplitude of the electric field is related to the intensity of the wave

by the relation

where

ϵ₀ is the electric permittivity of free space(vacuum) and is equal to 8.85 × 10^-12 C² N^-1 m^-2, C is the speed of light in vacuum and is equal to 3 × 10⁸ m s^-1 and E₀ is the amplitude of electric field.

.

The amplitudes of electric and magnetic fields are related as

where B₀ is the amplitude of magnetic field in free space.

Thus the value of magnetic field will be

.

The electric field amplitude is and the magnetic field amplitude is .