The quantum theory of light, also known as quantum electrodynamics (QED), is a theoretical framework that describes the behavior of electromagnetic radiation, including light, at the quantum level. This theory was developed in the early 20th century by physicists such as Albert Einstein, Niels Bohr, and Max Planck.

The quantum theory of light, also known as quantum electrodynamics (QED), is a theoretical framework that describes the behavior of electromagnetic radiation, including light, at the quantum level. This theory was developed in the early 20th century by physicists such as Albert Einstein, Niels Bohr, and Max Planck.

According to quantum theory, electromagnetic radiation is quantized into discrete packets of energy called photons. The energy of a photon is directly proportional to its frequency, as described by the equation E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency of the electromagnetic radiation.

In addition to being particles, photons also exhibit wave-like behavior, as described by the wave-particle duality of quantum mechanics. This means that photons can exhibit interference and diffraction patterns when they interact with matter or other photons.

One of the key predictions of QED is that photons can interact with charged particles, such as electrons, through the emission and absorption of photons. This process is responsible for many phenomena, such as the photoelectric effect, where photons are absorbed by electrons in a material, causing them to be ejected and creating an electrical current.

Overall, the quantum theory of light has had a profound impact on our understanding of the nature of light and its interactions with matter, and has been crucial in the development of modern technologies such as lasers and solar cells.