What is a photon?

A photon is fundamentally defined as a particle of light. It is the basic unit or quantum of electromagnetic radiation, which includes not only visible light but also other forms of electromagnetic waves, such as infrared and ultraviolet light. Photons are unique because they exhibit both particle-like and wave-like properties, a phenomenon that is central to the field of quantum mechanics.

In addition to being a particle of light, photons carry energy that is directly related to their frequency; higher frequency photons have more energy than lower frequency ones. This characteristic plays a crucial role in various applications, including laser technology, where the manipulation and emission of photons are essential.

While other choices mention related concepts, they do not capture the fundamental nature of a photon as a discrete particle of light, which is why that definition is the most accurate. Understanding photons is key in various fields, including optics and laser applications, reinforcing their importance in science and technology.