Final answer:
Light exhibits wave-particle duality, with diffraction supporting its wave nature and the photoelectric effect supporting its particle nature. Light behaves as both a wave and a particle, and this complex nature cannot be fully depicted as solely one or the other.
Step-by-step explanation:
The two properties of light that indicate its wave-particle duality are diffraction and the photoelectric effect. Diffraction supports the wave model of light as it shows light bending around obstacles and spreading out from slits, which is characteristic behavior for waves. On the other hand, the photoelectric effect, which occurs when light dislodges electrons from a metal surface, supports the particle model of light. This is because the effect can only be explained if light is considered to be made of particles, known as photons, that carry discrete packets of energy.
The conclusion from these observations is that light behaves as both a wave and a particle. This dual behavior is described by the concept of wave-particle duality. Depending on the experiment, light can exhibit wave-like properties such as interference and diffraction, or particle-like properties as evidenced by the photoelectric effect. Despite extensive research, the full understanding of light's dual nature remains an underlying mystery in physics.