9.4 Light as a Wave or a Particle? Time Frame for Newton/Huygen • Newton (1643-1727) • Born in England • Huygen (1629 –1695) • Born in Holland What is the basis of each model/theory: Newton: _____________________ Huygens:______________________ Comparison Rectilinear Propagation Rectilinear Propagation Diffraction Diffraction Reflection Reflection Refraction Refraction Partial ReflectionPartial Partial Refraction ReflectionDispersion Partial Refraction Dispersion Explanation/Description Explained Well by the Explanation/ Explained Well Explained well Theory?by Huygens’ Description by the Newton’s Theory? Theory? Comparison… Rectilinear Propagation Reflection Diffraction Reflection Refraction Partial ReflectionPartial Refraction Explanation/Description Explained Well by the Explanation/ Explained Well Explained well Theory?by Huygens’ Description by the Newton’s Theory? Theory? - Light is absorbed fully on black surfaces yet particles reflect off any surface In summary, Huygens’wave theory explained many of the properties of light, including reflection, refraction, partial reflection– partial refraction, diffraction, dispersion, and rectilinear propagation. The wave theory was more valid at that time than Newton’s corpuscular theory, but because of Newton’s reputation in other areas of physics, the corpuscular theory would dominate for 100 years, …until Thomas Young provided new and definitive evidence in 1807. Read Section 9.5 1. What evidence did Thomas Young give to support the theory that light is a wave?