(c) Dr Paul Kinsler. [Acknowledgements & Feedback]
This is part of an information maze -- see the index-file for the full picture.
Photons are the particle associated with light. They carry both energy, momentum, and have a spin of 1. We describe photons by applying quantum-mechanics to the electro-magnetic-field.
Strictly speaking, a photon is not some kind of point particle zipping along at the speed of light through spacetime -- it is a single excitation of an appropriate solution (a "mode") of Maxwells-equations for the electro-magnetic-field.
The spin of the photon means that it can be polarized. Measurements (along a particular direction) of the spin components of spin 1 particles usually have three possible outcomes: -1, 0, +1. However, since photons travel at the speed of light, only two of these are allowed: hence we get vertically and horizontally polarized light; or, alternatively, left or right handed circularly polarized light.
XINDEX: spin, spacetime, light, electro-magnetic-waves, electro-magnetic-field, index-file.
20011228 1122 19990302 (c) Paul Kinsler
XKEYWORD: photon
Email Feedback: Dr.Paul.Kinsler@physics.org
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