Photon

In physics, the photon (from Greek φοτος, meaning light) is a quantum of the electromagnetic field, for instance light. Photons were originally called "energy quanta".

Related Topics:
Physics - Greek - Quantum - Electromagnetic field - Light - Energy

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The photon is one of the elementary particles. Its interactions with electrons and atomic nuclei account for a great many of the features of matter, such as the existence and stability of atoms, molecules, and solids. These interactions are studied in quantum electrodynamics (QED), which is the oldest part of the Standard Model of particle physics.

Related Topics:
Elementary particles - Electrons - Atomic nuclei - Atom - Molecule - Solid - Quantum electrodynamics - Standard Model - Particle physics

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In some respects a photon acts as a particle, for instance when registered by the light sensitive device in a camera. In other respects, a photon acts like a wave, as when passing through the optics in a camera. According to the so-called wave-particle duality in quantum physics, it is natural for the photon to display either aspect of its nature, according to the circumstances. Normally, light is formed from a large number of photons, with the intensity or brightness related to the number of them. At low intensity, it requires very sensitive instruments, used in astronomy or spectroscopy, for instance, to detect the individual photons.

Related Topics:
Particle - Camera - Optics - Wave-particle duality - Quantum physics - Intensity - Brightness - Astronomy - Spectroscopy

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