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photon

 
   
The elementary particle that corresponds to an electromagnetic wave (See wave-particle duality). It is the massless gauge boson for the electromagnetic interaction, and therefore travels at the speed of light in a vacuum. In the same way that normal modes of a crystal lattice can be considered as excitations called phonons, electromagnetic waves are also normal modes (but without a medium) whose energy is in units of hf, where h is the Planck constant and f is the frequency of the oscillation. Thus a photon carries an energy hf. It also carries a momentum Ñ›k, where k is the wave vector of the travelling wave. Photons can interact with other particles, particularly electrons, and this interaction is responsible for all the observable phenomena associated with electromagnetic radiation.  

 

 

 
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Other Terms : stereographic projection (stereogram) | streamline | Earth

 

 

 
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