Wave behavior is proven by diffraction, interference and the polarization of light. Shorter waves with higher frequencies have shorter periods. Monochromatic light has one frequency. Coherent light waves are all in phase. Real images are always inverted.
Virtual images are always upright.
The particle behavior of light is proven by the photoelectric effect. Large objects have very short wavelengths when moving and thus can not be observed behaving as a wave. All electromagnetic waves originate from accelerating charged particles. The lowest energy state of a atom is called the ground state. Increasing light frequency increases the kinetic energy of the emitted photo-electrons.