What is light?


Visible light (commonly referred to simply as light) is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has a wavelength in the range of about 380 nanometres to about 740 nm – between the invisible infrared, with longer wavelengths and the invisible ultraviolet, with shorter wavelengths.

Read more about Light.

Some articles on light:

Historical Theories About Light, in Chronological Order - Electromagnetic Theory As Explanation For All Types of Visible Light and All EM Radiation
... In 1845, Michael Faraday discovered that the plane of polarisation of linearly polarised light is rotated when the light rays travel along the magnetic field direction in the presence of a transparent dielectric, an ... This was the first evidence that light was related to electromagnetism ... In 1846 he speculated that light might be some form of disturbance propagating along magnetic field lines ...
Speed Of Gravity - Lorentz Covariant Models
... greater than c would contradict the concept of local time (based on synchronization by light signals) and the principle of relativity ... could communicate by signals other than those of light, the velocity of propagation of which differed from that of light? If, after having regulated our watches by the optimal method, we wished to verify the ... with a velocity a million times as great as that of light? However, in 1905 Poincaré calculated that changes in the gravitational field can propagate with the speed of light if it is ...
Color Temperature - Color Rendering Index
... rendering index (CRI) is a method to determine how well a light source's illumination of eight sample patches compares to the illumination provided ... a numerical estimate of what reference (ideal) light source best approximates a particular artificial light, and what the difference is ...
Flash - Light
... of very short and extremely bright flashes of light Arc flash, an electrical explosion Lightning, a natural phenomenon Muzzle flash, the visible light of the ...

More definitions of "light":

  • (adj): Less than the correct or legal or full amount often deliberately so.
    Example: "A light pound"
    Synonyms: scant, short
  • (adj): (used of soil) loose and large-grained in consistency.
    Example: "Light sandy soil"
    Synonyms: friable, sandy
  • (noun): A person regarded very fondly.
    Example: "The light of my life"
  • (adj): Of little intensity or power or force.
    Example: "The light touch of her fingers"; "a light breeze"
  • (noun): A condition of spiritual awareness; divine illumination.
    Example: "Follow God's light"
    Synonyms: illumination
  • (adj): Marked by temperance in indulgence.
    Example: "A light eater"; "a light smoker"; "ate a light supper"
    Synonyms: abstemious
  • (adj): Having a spongy or flaky texture; well-leavened.
    Example: "Light pastries"
  • (adj): Having relatively few calories.
    Example: "Light (or lite) beer"
    Synonyms: lite, low-cal
  • (adj): Moving easily and quickly; nimble.
    Example: "The dancer was light and graceful"; "walked with a light tripping step"
    Synonyms: lightsome, tripping
  • (adj): Used of vowels or syllables; pronounced with little or no stress.
    Example: "A syllable that ends in a short vowel is a light syllable"
    Synonyms: unaccented, weak
  • (noun): A particular perspective or aspect of a situation.
    Example: "Although he saw it in a different light, he still did not understand"
  • (noun): Mental understanding as an enlightening experience.
    Example: "He finally saw the light"; "can you shed light on this problem?"
  • (adv): With few burdens.
    Example: "Experienced travellers travel light"
    Synonyms: lightly
  • (adj): Having little importance.
    Example: "Losing his job was no light matter"
  • (noun): A device for lighting or igniting fuel or charges or fires.
    Example: "Do you have a light?"
    Synonyms: lighter, igniter, ignitor
  • (adj): Demanding little effort; not burdensome.
    Example: "Light housework"; "light exercise"
  • (adj): Intended primarily as entertainment; not serious or profound.
    Example: "Light verse"; "a light comedy"
  • (noun): Any device serving as a source of illumination.
    Synonyms: light source
  • (adj): (of sound or color) free from anything that dulls or dims.
    Example: "A light lilting voice like a silver bell"
    Synonyms: clean, clear, unclouded
  • (adj): Weak and likely to lose consciousness.
    Example: "Felt light in the head"; "light-headed with wine"; "light-headed from lack of sleep"
    Synonyms: faint, swooning, light-headed, lightheaded
  • (adj): Of comparatively little physical weight or density.
    Example: "A light load"; "magnesium is a light metal--having a specific gravity of 1.74 at 20 degrees C"
  • (adj): Designed for ease of movement or to carry little weight.
    Example: "Light aircraft"; "a light truck"
  • (noun): An illuminated area.
    Example: "He stepped into the light"
  • (adj): Very thin and insubstantial.
    Example: "Light summer dresses"
    Synonyms: flimsy
  • (noun): A visual warning signal.
    Example: "They saw the light of the beacon"; "there was a light at every corner"
  • (noun): Public awareness.
    Example: "It brought the scandal to light"
  • (verb): Cause to start burning; subject to fire or great heat.
    Example: "Light a cigarette"
    Synonyms: ignite
  • (adj): (used of color) having a relatively small amount of coloring agent.
    Example: "Light blue"; "light colors such as pastels"; "a light-colored powder"
    Synonyms: light-colored
  • (noun): The visual effect of illumination on objects or scenes as created in pictures.
    Example: "He could paint the lightest light and the darkest dark"
    Synonyms: lightness
  • (noun): Brightness and animation of countenance.
    Synonyms: sparkle, spark
  • (adj): Easily assimilated in the alimentary canal; not rich or heavily seasoned.
    Example: "A light diet"
  • (adj): Psychologically light; especially free from sadness or troubles.
    Example: "A light heart"
  • (adj): (physics, chemistry) not having atomic weight greater than average.
    Example: "Light water is ordinary water"
  • (adj): Characterized by or emitting light.
    Example: "A room that is light when the shutters are open"; "the inside of the house was airy and light"
  • (verb): To come to rest, settle.
    Synonyms: alight, perch
  • (noun): Having abundant light or illumination.
    Example: "They played as long as it was light"
    Synonyms: lighting
  • (adj): Silly or trivial.
    Example: "Light banter"; "light idle chatter"
    Synonyms: idle
  • (noun): (physics) electromagnetic radiation that can produce a visual sensation.
    Example: "The light was filtered through a soft glass window"
    Synonyms: visible light, visible radiation
  • (verb): Fall to somebody by assignment or lot.
    Synonyms: fall
  • (adj): Not great in degree or quantity or number.
    Example: "A light sentence"; "a light accent"; "casualties were light"; "light snow was falling"; "light misty rain"; "light smoke from the chimney"
  • (adj): (of sleep) easily disturbed.
    Example: "In a light doze"; "a light sleeper"
    Synonyms: wakeful
  • (adj): Of the military or industry; using (or being) relatively small or light arms or equipment.
    Example: "Light infantry"; "light cavalry"; "light industry"; "light weapons"

Famous quotes containing the word light:

    The night has a thousand eyes,
    And the day but one;
    Yet the light of the bright world dies
    With the dying sun.
    Francis William Bourdillon (1852–1921)

    When it is dark in the east, it is light in the west; when things are dark in the south there is still light in the north.
    Chinese proverb.

    Long enough I had heard of irrelevant things; now at length I was glad to make acquaintance with the light that dwells in rotten wood. Where is all your knowledge gone to? It evaporates completely, for it has no depth.
    Henry David Thoreau (1817–1862)