<P> The Tyndall effect, also known as Willis--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 these particles . </P> <P> Under the Tyndall effect, the longer - wavelength light is more transmitted while the shorter - wavelength light is more reflected via scattering . The Tyndall effect is seen when light - scattering particulate - matter is dispersed in an otherwise - light - transmitting medium, when the cross-section of an individual particulate is the range of roughly between 40 and 900 nanometers, i.e., somewhat below or near the wavelength of visible light (400--750 nanometers). </P>

The scattering of light by a colloidal suspension is called the