Light exhibits both wave-like and particle-like properties, depending on how it is observed and measured. This is known as the wave-particle duality of light. In certain experiments, light behaves as a wave, while in others it behaves as a particle.
The wave nature of light is evident in phenomena such as interference and diffraction. Interference occurs when two or more light waves combine and either reinforce or cancel each other out, creating a pattern of light and dark regions. Diffraction refers to the bending or spreading out of light waves as they encounter an obstacle or pass through a narrow opening, resulting in patterns of constructive and destructive interference.
On the other hand, the particle nature of light is observed in certain experiments, such as the photoelectric effect and the Compton effect. The photoelectric effect involves the ejection of electrons from a material when it is exposed to light of a sufficiently high frequency. The Compton effect demonstrates that light can transfer momentum and energy to particles like electrons when it interacts with them, which is characteristic of particles.
To explain these seemingly contradictory behaviors, the theory of quantum mechanics was developed. According to quantum mechanics, light can be described by entities called photons, which are quanta or packets of energy. These photons can exhibit both wave-like and particle-like behavior, depending on the experimental setup and observation.
In summary, light can be regarded as having both wave-like and particle-like properties, and its behavior is best understood within the framework of quantum mechanics.