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photon (electromagnetic radiation)
subject			fact

photon	has spin 1
	has synonym electromagnetic radiation
	carries the force electromagnetism
	has definition Smallest packet of the electromagnetic force field; messenger particle of the electromagnetic force; smallest bundle of light.
	has definition The quantum of the electromagnetic field. It is the massless spin-1 gauge boson of QED. Virtual photons mediate the electromagnetic force between charged particles. Virtual photons can also adopt a mass for a short period, in accordance with Heisenberg's uncertainty principle.
	has definition A transverse wave of electric and magnetic fields which can propagate through empty space.
	is a kind of carrier boson
	is a kind of neutral particle
	is a kind of massless particle
	is a kind of transverse wave
massless particle	has mass 0
neutral particle	is not accelerated by electric or magnetic fields
	has charge 0
wave	has propagation direction
particle	obeys uncertainty principle
	has frequency inversely proportional to the wavelength
	has wavelength inversely proportional to its momentum
boson	has quantum behavior Bose-Einstein statistics
harmonic motion	has amplitude
	has period
physical process	has domain physics
physical object	has location or center of gravity
	has angular momentum
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

Kinds of photon :

• gamma ray (1 kind, 11 facts) - Electromagnetic radiation similar to X-radiation, although of shorter wavelength, emitted spontaneously by some radioactive substances from atomic nuclei during radioactive decay., An electromagnetic wave with a wavelength in the range of 10^-13 to 10^-10 meter, corresponding to photons with energy in the range of 10⁴ to 10⁷ electron volts., Electromagnetic radiation with a wavelength less than about 1 Å (10^-10 m); blends from the "hard" X-ray region. Photons of energy greater than about 10 keV., Rays first discovered in radioactive material, and later identified as very high energy photons., Extremely short-wavelength electromagnetic energy., Photons of very high frequency and very short wavelength; the most energetic and penetrating form of electromagnetic radiation., Photon of very high frequency (wavelength shorter than a few tenths of an angstrom); the most energetic form of electromagnetic radiation, although there is no sharp boundary between γ-ray photon and an X-ray photon. Usually γ-ray photons come from the nucleus and X-ray photons come from the inner orbital electrons. Galactic γ-ray photons seem to originate primarily in the spiral arms.
• infrared (3 kinds, 14 facts) (IR) - That part of the electromagnetic spectrum that lies beyond the red, having wavelengths from about 7500 Å to a few millimeters (about 10¹¹-10¹⁴ Hz). Infrared radiation is caused by atomic transitions, or by vibrational (near-IR) and rotational (far-IR) transitions in molecules. (IRe1, IRc1, IRs1: the e sources are extended; the c sources are unresolved; the s indicates an infrared nebula surrounding a visible star.), The region of the electromagnetic spectrum from a wavelength of about 1 μm (10^-6 m) to about 200 μm. The region from 1 to 5 µm is the near infrared: 5-30 is the mid infrared and 30-200 µm is the far infrared.
• microwave (12 kinds, 41 facts) - An electromagnetic wave (in the radio region just beyond the infrared) with a wavelength of from about 1 mm to 30 cm (about 10⁹-10¹¹ Hz)., An electromagnetic wave with a wavelength between one millimeter and 30 centimeters, or sometimes one meter., Radiation in the electromagnetic spectrum between infrared and radio waves. This range has wavelengths of between about 20 cm and about 1 mm. Radiation of this type was detected as background radiation., Radio radiation with wavelengths of about 10^-4 to 1 meter, equal to 10⁹ to 10¹³ hertz.
• optical (7 kinds, 12 facts) (light) - Electromagnetic radiation with wavelengths of or close to those detectable by the eye.
• radio (9 kinds, 32 facts) - Electromagnetic radiation with the lowest energy and longest wavelength. Unlike visible light, radio waves penetrate dust and can be detected from throughout the Galaxy.
• ultraviolet (2 kinds, 10 facts) (UV) - Part of the electromagnetic spectrum immediately above visible light (but below gamma-rays and X-rays); it therefore comprises a range of radiation of shorter wavelength and higher frequency than those of visible light., Electromagnetic radiation of a wavelength slightly shorter than that of visible light., Electromagnetic radiation "beyond the violet" with wavelengths in the approximate range 100-4000 Å.
• X-ray (2 kinds, 7 facts) - Photon of wavelength between about 0.1 Å and 100 Å - more energetic than ultraviolet, but less energetic than a γ-ray., A large band of electromagnetic radiation with wavelengths smaller than extreme ultraviolet light. A typical X-ray photon has over one thousand times as much energy as a photon of visible light.

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