Answer to Question #156665 in Physics for Saskia

Question

Particulate nature of light: Describe one experiment or observation that shows that light has wave properties and one experiment or observation that shows that it behaves as a stream of particles. Ensure that you explain precisely how each experiment leads to that conclusion.

Answer 1

An experiment or observation that shows that light has wave properties: take a large slightly converging lens and put it on a flat glass, carefully push the lens toward the glass. Shine it with sunlight. You will see a set of colorful rings near the spot where the lens is in contact with the glass. What you see is called 'Newton's Rings,' a phenomenon possible due to interference of light: there are minima and maxima of light intensity.

An experiment or observation that shows that it behaves as a stream of particles: take a flat glass or mirror and shine it with with a flashlight or sun. You will see a spot of reflected light. Reflection of light shows particle nature of light: seems like photons behave like small balls that rebound from a reflective surface and the angle of incidence is equal to the angle of reflection, like with regular balls we use to play soccer or basketball.