Photons are fundamental particles of light and other forms of electromagnetic radiation. They are the smallest quantized units of electromagnetic energy and are considered to be both particles and waves, exhibiting properties of both particles and waves.
Photons are massless particles that travel at the speed of light in a vacuum, denoted as "c" in physics. They have no electric charge, and their behavior is governed by the laws of quantum mechanics.
The primary role of photons is to carry electromagnetic energy. They are responsible for transmitting electromagnetic radiation, which includes visible light, radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, and gamma rays. Each of these types of radiation corresponds to photons with different energies and wavelengths.
When photons interact with matter, several things can happen. They may be absorbed by atoms or molecules, transferring their energy to the absorbing material. This energy can be used to excite electrons to higher energy levels or cause other atomic or molecular changes. Absorbed photons are often the basis for various scientific and technological applications, such as solar cells.
Photons can also be scattered or reflected by matter. In these cases, the direction of the photon's propagation may change, but its energy remains the same. Reflection is responsible for the way we see objects, as light is reflected off their surfaces and into our eyes.
Moreover, when photons pass through transparent materials like glass or water, they may experience refraction, causing a change in their direction and speed. This phenomenon is responsible for effects like the bending of light in a prism.
In summary, photons are the basic units of electromagnetic energy. They carry energy, transmit electromagnetic radiation, and interact with matter through processes such as absorption, scattering, reflection, and refraction.