visible light

(noun)

the part of the electromagnetic spectrum, between infrared and ultraviolet, that is visible to the human eye

Related Terms

Examples of visible light in the following topics:

  • Visible Light

    • Visible light is the portion of the electromagnetic spectrum that is visible to the human eye, ranging from roughly 390 to 750 nm.
    • Visible light, as called the visible spectrum, is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye.
    • Visible light is produced by vibrations and rotations of atoms and molecules, as well as by electronic transitions within atoms and molecules.
    • Colors that can be produced by visible light of a narrow band of wavelengths (monochromaticlight) are called pure spectral colors.
    • This allows visible light to heat the surface.

  • Infrared Waves

    • Infrared (IR) light is EM radiation with wavelengths longer than those of visible light from 0.74 µm to 1 mm (300 GHz to 1 THz).
    • Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 0.74 micrometers (µm) to 1 mm.
    • Near-infrared, from 120 to 400 THz (2,500 to 750 nm) - Physical processes that are relevant for this range are similar to those for visible light.
    • Infrared light from the Sun only accounts for 49% of the heating of the Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths.
    • Visible light or ultraviolet-emitting lasers can char paper and incandescently hot objects emit visible radiation.

  • Introduction to Light Energy

    • All electromagnetic radiation, or light energy, travels at a particular wavelength and carries a certain amount of energy.
    • The sun emits an enormous amount of electromagnetic radiation (solar or light energy).
    • Humans can see only a fraction of this energy, which is referred to as "visible light."
    • Visible light constitutes only one of many types of electromagnetic radiation emitted from the sun and other stars.
    • All electromagnetic radiation, including visible light, is characterized by its wavelength.

  • Absorption of Light

    • For example, retinal pigments can only "see" (absorb) 700 nm to 400 nm light; this is visible light.
    • The visible light seen by humans as the color white light actually exists in a rainbow of colors in the electromagnetic spectrum, with violet and blue having shorter wavelengths and, thus, higher energy.
    • Different kinds of pigments exist, each of which has evolved to absorb only certain wavelengths or colors of visible light.
    • Each type of pigment can be identified by the specific pattern of wavelengths it absorbs from visible light, which is the absorption spectrum.
    • The colors of visible light do not carry the same amount of energy.

  • Light

    • Light can, in fact, travel in a vacuum.
    • A glance at the electromagnetic spectrum shows that visible light for humans is just a small slice of the entire spectrum, which includes radiation that we cannot see as light because it is below the frequency of visible red light and above the frequency of visible violet light .
    • Light at the red end of the visible spectrum has longer wavelengths (and is lower frequency), while light at the violet end has shorter wavelengths (and is higher frequency).
    • The term "white light" is light that is perceived as white by the human eye.
    • A glance at the electromagnetic spectrum shows that visible light for humans is just a small slice of the entire spectrum.

  • Ultraviolet Light

    • Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light in the range 10 nm to 400 nm.
    • Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, that is, in the range 10 nm to 400 nm, corresponding to photon energies from 3 eV to 124 eV (1 eV = 1.6e-19 J; EM radiation with frequencies higher than those of visible light are often expressed in terms of energy rather than frequency).
    • UV light is found in sunlight (where it constitutes about 10% of the energy in vacuum) and is emitted by electric arcs and specialized lights such as black lights.
    • This is a plot of Earth's atmospheric opacity (opposite of transmittance) to various wavelengths of electromagnetic radiation, including visible light.
    • Visible light passes relatively unimpeded through the atmosphere in the "optical window."

  • Plant Responses to Light

    • Plants respond to light stimuli by growing, differentiating, tracking the time of day and seasons, and moving toward or away from the light.
    • Plants can differentiate and develop in response to light (known as photomorphogenesis), which allows plants to optimize their use of light and space.
    • The red, far-red, and violet-blue regions of the visible light spectrum trigger structural development in plants.
    • Sensory photoreceptors absorb light in these particular regions of the visible light spectrum because of the quality of light available in the daylight spectrum.
    • Water absorbs red light, which makes the detection of blue light essential for algae and aquatic plants.

  • Background

    • Although we see sunlight (or white light) as uniform or homogeneous in color, it is actually composed of a broad range of radiation wavelengths in the ultraviolet (UV), visible and infrared (IR) portions of the spectrum.
    • As shown below, the component colors of the visible portion can be separated by passing sunlight through a prism, which acts to bend the light in differing degrees according to wavelength.
    • Electromagnetic radiation such as visible light is commonly treated as a wave phenomenon, characterized by a wavelength or frequency.
    • The longest visible wavelength is red and the shortest is violet.
    • Thus, absorption of 420-430 nm light renders a substance yellow, and absorption of 500-520 nm light makes it red.

  • Dispersion of the Visible Spectrum

    • Within the electromagnetic spectrum, there is only a portion that is visible to the human eye.
    • Visible light is the range of wavelengths of electromagnetic radiation that humans can see.
    • When a light ray enters a medium with a different index of refraction, the light is dispersed, as shown in with a prism.
    • When white light enters the prism, it spreads.
    • (b) White light is dispersed by the prism (shown exaggerated).

  • Dispersion: Rainbows and Prisims

    • These colors are associated with different wavelengths of light.
    • White light, in particular, is a fairly uniform mixture of all visible wavelengths.
    • Sunlight, considered to be white, actually appears to be a bit yellow because of its mixture of wavelengths, but it does contain all visible wavelengths.
    • Thus violet light is bent more than red light and the light is dispersed into the same sequence of wavelengths .
    • (b) White light is dispersed by the prism (shown exaggerated).