Newton's Corpuscular theory of light

[jmorris]

In 1672 Newton suggested that light was composed of tiny particles called corpuscles

At the time light was known to reflect and refract. Newton could explain both reflection and refraction using his corpuscular theory and his own laws of motion.

He explained reflection as a force that pushed away the corpuscles from the surface of a reflector. The velocity component parallel to the surface remained unchanged.

He said that the effects of refraction were due to the fact that the corpuscles traveled faster in a denser medium due to a force of attraction. The velocity component parallel to the surface remained unchanged, whilst the velocity component perpendicular to the surface increased, causing the corpuscles to speed up and therefore move towards the normal.