Why is glass transparent?

Answer 1

You have probably noticed that most liquids and gases are transparent. Water, cooking oil, rubbing alcohol, air, natural gas, etc. are all clear. That's because of a fundamental difference between solids, liquids and gases. When a substance is in its solid state, normally its molecules are highly organized in relation to one another, strengthening the bond between them and giving the substance rigidity. As the substance changes from a solid to a liquid, however, the strength of the bond lessens and the molecules begin to align themselves randomly. If we follow the substance's progression to a gas, we see that the molecular bond is greatly weakened and the relationship of the molecules to one another is almost completely random.

This progression from ordered to random organization is the primary reason that light can pass through liquids and gases. Just like bricks stacked neatly on top of one another, the ordered molecules of most solids are virtually impenetrable to light waves. Depending on the substance, the light waves will be reflected, scattered, absorbed or, more likely, some combination of the three. But as the substance changes to liquid or gas and the molecules are not stacked neatly anymore, gaps and holes occur that allow portions of the light waves to pass through. The greater the randomness of the molecular organization of the substance, the easier it is for the light to pass through.

Another factor happens at the sub-atomic level. The atoms that bind together to make the molecules of any particular substance have electrons, usually lots of them. When photons come in contact with these electrons, the following can occur:

* An electron absorbs the energy of the photon and transforms it (usually into heat)
* An electron absorbs the energy of the photon and stores it (this can result in luminescence, which is called fluorescence if the electron stores the energy for a short time and phosphorescence if it stores it for long time)
* An electron absorbs the energy of the photon and sends it back out the way it came in (reflection)
* An electron cannot absorb the energy of the photon, in which case the photon continues on its path (transmitted)

Most of the time, it is a combination of the above that happens to the light that hits an object. The electrons in different materials vary in the range of energy that they can absorb. A lot of glass, for example, blocks out ultraviolet (UV) light. What happens is the electrons in the glass absorb the energy of the photons in the UV range while ignoring the weaker energy of photons in the visible light spectrum. If the electrons absorb the energy of any portion of the visible spectrum, the light that transmits through will appeared colored according to the portion of the spectrum absorbed. In fact, the color of any object is a direct result of what levels of energy the electrons in the substance will absorb!

Although forms of glass, such as obsidian or volcanic glass, can occur naturally, Glass is generally a manmade substance. Here is the basic way to make glass:

* Take the most common glass material, silica, which is just plain old sand like you would find on the beach.
* Heat it to an extreme temperature until it becomes liquid, then cool it.

The resulting substance has a molecular structure that is very random like a liquid yet that retains the strong bond and rigidity of a solid. This is a simplification of the process. Usually you add both a substance to make the silica melt quicker and something else to stabilize it so that the glass is not brittle and easily broken. The temperature, heating time and cooling method must all be very exact.

The materials used for glass-making cool to form an amorphous mix of molecules (like a liquid) and have electrons that do not absorb the energy of photons in the visible spectrum. This is why you can see through glass, but not wood, metal or stone, which are all solids.

A similar method, called quenching, is used with plastics to make them transparent or translucent. Quenching causes the polymers (long-chain molecules) in the plastic to settle into a random pattern that allows light to pass through. You can even use this process with organic substances. Clear or translucent candy is created by heating the ingredients of the recipe and then rapidly cooling them.

Notice that clear glass, clear plastic and clear candy are all solids that are melted and then cooled. Same process!

Thousands of different substances are used to make various forms of glass. How much and what type of light is transmitted depends on the type and purity of the substance used. Silica, in its purest form, transmits light well. Very little of the light wave is absorbed, but some of it is usually reflected. Look at almost any window and you will see this is true.

Other materials used to make glass may transmit or block specific types of light, such as ultraviolet light, or even parts of the visible spectrum. You have probably seen glass that was black or some other opaque color. Most often the color is caused by microscopic particles suspended in the glass, like the impurities we talked about in some liquids and gases. Another way to change the properties of the glass, such as filtering specific wavelengths of light, is to slow down the cooling process enough to allow the molecules to partially crystallize, or form pattern. And finally, some materials are chosen because they can be shaped and made to transmit and/or refract light in specific ways to use, for instance, as eyeglass lenses or as a magnifying glass.

Answer 2

glass is not slow moving liquid thats why the glass is transparent because the photon has less amount of power to put the electron at higher state and the photon just pass through

Answer 3

Also glass is actually a slow moving liquid. This can be proved by looking at the glass from rose windows in old cathedrals, its thicker at the base then it is at the top of the glass pane because over the centuries the mass has veeery slowly moved downwards. glass is made by melting soda ash, calcium carbonate, silica (sand) and other materials like zinc, antimony and lead. The lead helps to make the glass transparent, thats why lead crystal has a high lead content. Its all about a thing called the light refraction index but thats hard to explain in a few sentances without getting all technical. Coloured glass is made by batching up a clear melt (silica, soda ash and potash) to around 1300C and adding various metal oxides; frinstance potassium dichromate makes that wine bottle green colour, gold chloride gives you ruby red, manganese gives you purple, and cobalt oxide gives you cobalt blue. Also transparent glass is actually greenish because of the small iron content in silica sand.........by adding a pinch of manganese the glass turns greyish and transparent. Thank the Egyptians and Romans for discovering glass blowing, especially the glass artists on murano in the Venice lagoon, they still make glass there to this day. Its probable that the Chinese artisans and potters discovered glass by heating their pottery glazes without the pottery, then traded the technology with the Egyptians, or Persians around modern day Itaq. The history books tell us that Plato writes of its invention when cooking pots were placed on a mix of sand and some other ingredient that Ive forgotten (pthalo something).....but i dont believe it coz they would have had to be some very freaking hot cooking pots.

Answer 4

The structure allows wave lengths of visible light to pass through. Depending on the glass then it is opaque to other wave lengths like IR or UV.

Answer 5

You look to think of that sand isn't sparkling. it is. in case you %. up a single grain of (white) sand, you will see that mild shines by way of it. Its color (brought about by utilising minerals trapped interior) diffuses the mild, so as that maximum sand is 'translucent' particularly than 'sparkling', or completely sparkling. you besides mght look to think of that tumbler is sparkling. it is no longer. in case you wreck or weigh down sheet glass, you will discover that the smaller the products, the fewer sparkling it style of feels. If the products are as small as grains of sand, it is going to be basically as complicated to determine by way of them. Sheets of glass are purely needless to say sparkling as a results of fact of their parallel surfaces. Even particularly distorted surfaces will start to wreck the readability of the image you notice interior the path of the sheet. the exterior of a tumbler sheet is many times dealt with (to make 'privateness' glass, as an occasion) with acid. This etches the exterior inconsistently, and thoroughly disrupts the transmission of sunshine. The sheet turns into translucent. colored glass blocks mild different than the colour you notice. Breaking or etching colored glass produces a great much less sparkling effect than you get with sparkling glass. a number of 'organic' (volcanically fused) glass, which includes Obsidian, is fairly deeply colored, so as that curiously opaque. Sand is many times deeply colored (yellow, brown or maybe black sands are very ordinary), as a results of fact it became produced from opaque components.

Answer 6

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Answer 7

Because visible light goes thru it?