photons. Light waves are very similar to sound waves, but can move much faster. Sound travels at about 1090 feet per second or 330 meters per second while light travels at 186,000 miles per second or 299792.458 kilometers per second. In equations, the speed of light is often written as the letter C. Another difference between light and sound waves is that while sound must have some form of matter in which to travel, such as air or water, light can travel through the vacuum of space. That is how light from the sun gets to us or how we can see the light from distant stars.Within the visible light of the electromagnetic spectrum are still more wavelengths. Each wavelength is perceived by our eyes as a different color. The shorter wavelengths of visible light are violet — we might call them purple. Then as the wavelengths get longer and longer, the visible light changes in color to blue, green, yellow, orange, and finally the longest, which is red.

Some animals can see waveslengths of light that humans cannot. Those waveslengths would be just outside the edges of human visible light. For example, insects can see ultraviolet waves — waves just before purple on the electromagnetic spectrum. But we are not able to see these. At the same time, there are colors of red that insects are unable to see, but that humans can.

Most light that we use — like sunlight or light from a light bulb — is actually a mixture of all of the visible light wavelengths. It is called white light. When it is mixed, it is difficult for us to separate the colors out. We just see it as useful light. But at certain times the light does get separated out.

1.

to gather (a gas, liquid, or dissolved substance) on a surface in a condensed layer:Charcoal will adsorb gases.
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface.^[1] This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) is dissolved by or permeates a liquid or solid (the absorbent), respectively.^[2] Adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of it. Adsorption is a surface phenomenon.

IUPAC Definition

Increase in the concentration of a substance at the interface of a condensed and a liquid or gaseous layer owing to the operation of surface forces.Note 1: Adsorption of proteins is of great importance when a material is in contact with blood or body fluids. In the case of blood, albumin, which is largely predominant, is generally adsorbed first, and then rearrangements occur in favor of other minor proteins according to surface affinity against mass law selection (Vroman effect).Note 2: Adsorbed molecules are those that are resistant to washing with the same solvent medium in the case of adsorption from solutions. The washing conditions can thus modify the measurement results, particularly when the interaction energy is low.^[3]

Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.^[4]

Adsorption is present in many natural, physical, biological and chemical systems and is widely used in industrial applications such as heterogeneous catalysts,^[5][6] activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increasing storage capacity of carbide-derived carbons and water purification. Adsorption, ion exchange and chromatographyare sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Pharmaceutical industry applications, which use adsorption as a means to prolong neurological exposure to specific drugs or parts thereof,^{[citation needed]} are lesser known.

The word "adsorption" was coined in 1881 by German physicist Heinrich Kayser (1853-1940).

The Munsell color system, the first formal color notation system (1905), names only five "principal hues": red, yellow, green, blue, and purple (although note that Munsell's purple is not a spectral hue).^{[citation needed]}

Another traditional mnemonic device has been to turn the initial letters of seven spectral colors into a sentence. In Britain the most common is "Richard Of York Gave Battle In Vain." The mnemonic is said to refer to the defeat and death of Richard, Duke of York at the Battle of Wakefield. To avoid reference to this defeat, people from Yorkshire developed the alternative "Rowntrees Of York Gave Best In Value."^{[citation needed]} Alternatively, the biblically inspired "Read Out Your Good Book In Verse," or the more anarchic "Rinse Out Your Granny's Boots In Vinegar," may be used.