Light exhibits properties of both waves and particles, and its nature is best described by the theory of quantum mechanics.
According to classical physics, light was considered to be a wave. It was described by James Clerk Maxwell's equations, which explained its behavior in terms of electromagnetic waves. This wave nature of light explained phenomena such as interference, diffraction, and polarization.
However, in the early 20th century, experiments like the photoelectric effect and the double-slit experiment demonstrated that light also behaves like a particle. These observations led to the development of the theory of quantum mechanics, which introduced the concept of photons.
In quantum mechanics, light is described as consisting of discrete packets of energy called photons. Photons are quantized units of light that possess both particle-like and wave-like properties. When light interacts with matter, it can exhibit particle-like behavior, such as the ability to transfer discrete amounts of energy to electrons during the photoelectric effect.
On the other hand, light also exhibits wave-like properties, such as interference and diffraction, which are characteristic of waves. The wave nature of light is evident in phenomena like the interference patterns produced by a double-slit experiment, where light waves interfere with each other to create patterns of light and dark regions.
The concept of wave-particle duality, which is a fundamental principle of quantum mechanics, states that particles like photons can exhibit both wave-like and particle-like behavior depending on the experimental setup and the observed phenomena. This duality applies not only to light but also to other elementary particles, such as electrons and protons.
So, in summary, light is best described as having both wave and particle properties. Its behavior can be understood in terms of waves (electromagnetic waves) and particles (photons), depending on the specific experiment or phenomenon under consideration.