The
Tyndall effect, also known as
Tyndall scattering, is
light scattering by particles in a
colloid or else particles in a very fine
suspension. It is named after the 19th-century physicist
John Tyndall. It is similar to
Rayleigh scattering, in that the intensity of the scattered light depends on the fourth power of the frequency, so blue light is scattered much more strongly than red light. An example in everyday life is the blue colour sometimes seen in the smoke emitted by
motorcycles, in particular
two-stroke machines where the burnt engine oil provides the particles.