B What happens to absorbed colors in colored substances?

[Karagoz]

They say that substances have color because when light waves of all colors hit the substance, the atoms do absorb all the colors, except those that is its color.

Red substance is red because it absorbs all the color waves, but reflects the red waves.

But all the color waves the red substance absorbs, what happens to them? The atoms of the substance re-emit these waves right away at the same frequency? Or they emit at other frequency?

 

[ZapperZ]

They say that substances have color because when light waves of all colors hit the substance, the atoms do absorb all the colors, except those that is its color.

Red substance is red because it absorbs all the color waves, but reflects the red waves.

But all the color waves the red substance absorbs, what happens to them? The atoms of the substance re-emit these waves right away at the same frequency? Or they emit at other frequency?

What you must first understand is that a "solid" is different than an "atom".

A solid has MORE stuff going for it than isolated atoms. There is something called "vibrational" spectrum, where the atoms that make up a solid can vibrate. There are also many other "collective" properties of a solid that are not present in isolated atoms. Most, if not all, of the common properties of a solid are due to such collective properties.

An absorbed light can do many things. One of them is that it causes greater the lattice vibration, i.e. the atoms in the solid to vibrate more vigorously. This is what we normally call heat. It is why a metal left in the sun gets heated up, because the absorbed energy has been converted into heat (vibration).

Zz.

 

[russ_watters]

But all the color waves the red substance absorbs, what happens to them? The atoms of the substance re-emit these waves right away at the same frequency? Or they emit at other frequency?

They are immediately converted to thermal energy and depending on the conditions may then be re-radiated at a lower frequency or just lose heat via convection or conduction. For example, objects on Earth are warmed by the sun, absorbing its energy which is in large part composed of the visual spectrum. Then they get hot and re-radiate infrared and also lose heat to conduction and convection.

 

[pixel]

They say that substances have color because when light waves of all colors hit the substance, the atoms do absorb all the colors, except those that is its color.

In addition to absorption, there could be wavelength-dependent scattering e.g. if pigments are present.