How does Corpuscular Theory and  Wave Theory of Light affects the characteristics of light such as 1.speed of light, 2.rectilinear propagationwhat theory is the best and why

Expert Answers
enotechris eNotes educator| Certified Educator

These two viewpoints go back to the first discussions of the nature of Light.  the Corpuscular Theory, proposed by Isaac Newton (1642-1727) was that light is made up of tiny particles, or corpuscles. This theory required that light actually travel faster in denser mediums.  The Wave Theory, proposed by Christian Huygens (1629-1695) was that light was made up of waves traveling through the "Ether."  Rectilinear propagation suggests that light moves in a straight line, but as a wave, light can be diffracted.

Post-Quantum physics considers light to be a wave with some material properties; sometimes it acts like a wave, somtimes like a particle.  Exploring the mystery of the Nature of Light actually brought about the Quantum Revolution in Physics in the late 1800's.