A Photon is a Particle of light (Electromagnetic Radiation), i.e., what you call
such a particle if light is considered a stream of particles. It
is the Quantum of light, the minimum possible amount.
The photon theory, i.e., the modern particle theory of light,
is that the minimum amount of light depends upon the light's
Frequency, being the lightenergy proportional to it.
Dating from prior to photon theory, there has been a very successful
theory that EMR consists of waves, as summarized by Maxwell's Equations.
Photon theory coexists because it is successful in modeling
some light/matter interactions that the wave theory does not.
Photons are elementary particles (a type of Boson) according to
current particle physics, interacting with other particles. They
naturally travel "the speed of light". As implied above, each
photon has an assigned frequency and carries an amount of energy
proportional to it.
Phenomena successfully modeled with photon theory includes the
interaction of light with atoms and electrons, such as Absorption,
Emission and scattering. The first such instance for
photon theory was Photoionization, i.e., that ionization by
incoming EMR does not simply depend upon the total light energy
striking the atoms, but more basically on the light's frequency, which
Einstein explained as suggesting only those quanta of light
carrying sufficient energy to free an electron from the atom were
successful ionizing such an atom.
(physics,quantum mechanics)
http://en.wikipedia.org/wiki/Photon
Referenced by:
Absorption
Antimatter
Astronomical Quantities
Atomic Excitation
Balmer Jump
Baryon Acoustic Oscillations (BAO)
Baryon
Biofluorescence
Bohr Model
BoseEinstein Statistics
Bremsstrahlung
Cosmic Microwave Background (CMB)
CMB Lensing
CMB Polarization
CNO Cycle
Column Density
Compton Scattering
Continuous Absorption
Continuum Emission
Cooling Function
Cosmic Rays (CR)
Cherenkov Telescope Array (CTA)
Dark Matter
Dark Matter Annihilation
de Broglie Wavelength
Doppler Broadening
Electron Degeneracy
Electron Orbital
Electron Scattering
Emission
Epoch of Reionization (EOR)
Escape Fraction
Frequency
Gamma Rays
HighAltitude Water Cherenkov Observatory (HAWC)
Hydrogen (H)
Line Blanketing
LymanWerner Photon
Mean Free Path
Milagro
Neutrino (ν)
Optical Depth (τ)
Oscillator Strength
Pair Production
Particle
Photochemistry
Photodissociation
Photoionization
Photometer
Photon Counting
Photon Noise
Photosphere
Planck Constant (h)
Power Law
PoyntingRobertson Effect
Poynting Vector (S)
Pressure Integral
Quantum Mechanics (QM)
Quantum Number
Random Walk
Recombination
Equation of Radiative Transfer (RTE)
Superluminous Supernova (SLSN)
Spectral Power Distribution (SPD)
Synchrotron SelfCompton (SSC)
Standard Model
State of Excitation
Strömgren Sphere
Supersymmetry
Synchrotron Radiation
SunyaevZel'dovich Effect (SZ Effect)
Thermodynamic Equilibrium (TE)
Thomson Scattering
UltraHighEnergy Gamma Rays (UHEGR)
VeryHighEnergy Gamma Rays (VHEGR)
Vegetation Red Edge (VRE)
Wavelength
XMMNewton
