A photon is a fundamental particle of light and other forms of electromagnetic radiation. It is the carrier of the electromagnetic force, which is responsible for phenomena like light, radio waves, and X-rays. Photons have the following key characteristics:
- No Mass: Photons are massless particles, which allows them to travel at the speed of light (approximately 299,792 kilometers per second in a vacuum).
- Energy: While photons have no rest mass, they do have energy. The energy of a photon is directly proportional to its frequency (the number of oscillations per second) and inversely proportional to its wavelength (the distance between successive crests or troughs of the wave). The relationship between energy, frequency, and wavelength is given by the equation: E=h⋅fE = h \cdot f where EE is energy, hh is Planck’s constant, and ff is the frequency of the photon.
- Wave-Particle Duality: Photons exhibit both wave-like and particle-like properties. As waves, they can be described by electromagnetic fields that oscillate in space. As particles, they can be thought of as discrete packets of energy (quanta).
- Interactions: Photons interact with matter in various ways, such as being absorbed or emitted by atoms. When electrons in atoms move between energy levels, photons are often involved in these transitions.