Revise GCSE Physics

Question:Why do most lasers produce an intense coherent beam of light?

Because laser generate photons by copying other photons.

The laser beams have the following advantages.

All the waves (or particles) have the same frequency - this means that they are identical, same frequency means same energy and wavelength.

All the waves are in phase with each other - all the peaks arrive at the same time so that their effects can add together - we call this being coherent.

All the waves have low divergence - a laser beam does not spread out as it travels, so the power of the laser beam is concentrated in a small spot which we call high intensity.