Why does light passes through transparent materials like glass and water?

Answer 1

We can see through glass because light passes through it. Our eyes only see objects — chairs, the phone, your computer, or even tinted glass — by processing light waves reflected off the object or absorbed by it.

Light is made up of waves of different sizes. But our eyes detect only certain wavelengths known as the visible spectrum, and each wavelength in the visible spectrum represents a different color. When something is clear, like glass, visible light passes straight through it without being absorbed or reflected. Wood, on the other hand, absorbs the light in wavelengths we can see.

To understand this on the atomic level, imagine electrons whizzing around in clearly defined paths, like cars on a racetrack. The racetracks are called energy levels, and they determine whether the material will absorb light. "Light is a photon and it has energy," says Carlo Pantano, professor of materials science and engineering at Penn State University. When the energy level of the electron is similar to the energy of the light, the electron absorbs the light. "That energy gets converted to heat," Pantano says. "That's why black things get hot." The electrons in a molecule of wood are at the right energy level to absorb visible light, but the electrons in a glass molecule are not.

Clear glass does not absorb visible light, but it does absorb other wavelengths: ultraviolet, which is what gives you a suntan, and infrared, or heat. But not all glass is clear. A stained glass window, for instance, may glow with all the colors of the spectrum — but we can still see through it. Remember, an object's color depends on which wavelengths of light are absorbed and which are reflected.

Glass is colored by adding light-absorbing substances. Copper absorbs light in the red end of the spectrum, letting the blue end of the spectrum pass through. Adding copper to glass yields a blue pane. Chromium soaks up some red and blue wavelengths; glass spiked with chromium appears green. Because some visible wavelengths pass through colored glass, we can still see through it.

Answer 2

Hi Gaurav, Let me extend your question a little. Why is anything transparent? When light encounters a material, it can interact with it in several different ways. These interactions depend on the nature of the light (its wavelength, frequency, energy etc.) and the nature of the material (how closely packed its atoms or molecules are, whether those atoms or molecules are ordered, whether the electron orbitals are spaced such that they absorb light of certain frequencies and so on). For instance, light falling onto a leaf encounters a number of pigment molecules, predominantly chlorophyll. These molecules absorb light from the red and blue ends of the visible spectrum. The remaining light is scattered back because molecules in a leaf are quite tightly packed and so we see a green leaf. When light falls onto a block of metal, it encounters atoms that are tightly packed in a regular lattice and a "sea" of electrons moving between the atoms. Most of the light is scattered back from this kind of material, which is why we see a shiny metal surface. Glass is often referred to as a liquid, but really it has properties of both a solid (its molecules don't move very much) and a liquid (the molecules are not arranged in any kind of ordered way). Molecules in glass are not packed into a tight lattice and unless tinted, it doesn't contain molecules that capture light with a particular energy. So when light encounters glass, most of it passes straight through. Hence, it is transparent. Hope this helped answer your question, Shama

Answer 3

Because the transparent materials do not absorb light.

Light is made up of 7 colours of the rainbow.

For example, a red cloth reflects red light and absorbs all others.
A white cloth reflects all colours of the spectrum, because all the colours mixed together gives white.

So transparent materials do not absorb any, nor reflect any, and therefore don't appear to have a colour.

Answer 4

That pretty much IS the definition of transparency. A transparent object will have a certain frequency range that can transmit thru it, while it will block other frequencies. The different colors of light are all different, but similar frequencies. Glass will allow visible light through it since it is transparent to visible light, but it is opaque to say, infrared light which is just light at a different frequency. But then, infrared light can pass thru smoke which is opaque to visible light.

Different filters.

Answer 5

Light is composed of energy particles called photons, that move as electromagnetic waves. When light encounters an object like glass and water (which are very different, but for the sake of argument...) it moves relatively unobstructed because the photons are not being absorbed by the valence bands of the material's electron field. If they are not absorbed, the photons are repulsed and are reflected out of the materials' individual molecules and back into the ambience (e.g. your eye).

Answer 6

Its the other way round - objects are called transparent if light passes through them.

Answer 7

Lowboat got it. I was going to answer, but no point. Light is made of photons. Photons can pass through untinted glass and clear water (though not unchanged).

Answer 8

the wavelength of Visable light pass through glass with minimum distortion but other wave lengths can be effected in different ways. UV and IR may not pass through -- think sunglasses. Xrays and other wavelengths will pass through steel, bone ,brick. It just depends on wavelength. Some wave lengths will not even pass through air alpha and some beta particles. ....

Answer 9

They contain nothing to obsorb or reflect light.

Thus they're transparent.

Cheers.

Answer 10

B/c they ARE transparent. They act like a prism and allow light to filter through.