Which Experiment Best Demonstrates the Particle Nature of Light?

[jinksys]

Homework Statement

The particle nature of light is best illustrated by which of the following?
1) The scattering of alpha particles from gold foil.
2) The fact that hot objects emit electromagnetic radiation.
3) The diffraction pattern observed when a beam of electrons is scattered by a crystal
4) The fact that a rainbow consists of a continuous spectrum of colors.
5) The ejection of electrons from a metal surface illuminated by light.

Homework Equations

The Attempt at a Solution

My guess is #5 or #2, because they both have to do with electrons changing energy levels and emitting (or absorbing) electrons.

 

[diazona]

Actually, #2 doesn't have to do with electrons changing energy levels. The EM radiation emitted by hot objects is called blackbody radiation, and it's a purely thermal phenomenon (it occurs in all sort of hot objects whether they have electrons or not).