What is a photon?

A photon is defined as a particle packet of electromagnetic radiation. This characteristic allows us to understand the fundamental nature of light and other forms of electromagnetic waves. Photons are massless particles that carry energy and momentum, and they exhibit both wave-like and particle-like properties, which is central to the concept of wave-particle duality in quantum mechanics.

When we refer to a photon, we are talking about the smallest quantum of electromagnetic radiation, which includes visible light, ultraviolet light, infrared light, X-rays, and gamma rays. Each photon travels at the speed of light in a vacuum and is associated with a specific frequency and wavelength, determining its energy.

Understanding photons is essential for various applications in physics, including optics, quantum mechanics, and the study of energy transfer. Their behavior is fundamental to technologies such as lasers, solar cells, and various forms of imaging.

The other options discuss particles that are not related to electromagnetic radiation; electrons, neutrons, and alpha particles belong to different categories and have distinct roles in atomic and nuclear physics, which sets them apart from the definition of a photon.