What makes materials transparent

Sand, on the other hand, is also silicon dioxide, but it is so filled with impurities that light simply scatters outward incoherently and does not pass through to a noticeable extent. Pure metals reflect light but do not transmit it, because they are filled with free electrons.

These electrons reradiate the light in the direction opposite from which it arrived reflection , but they interfere with the light that would proceed in the forward direction, preventing transmission. She adds some details about the role of physical structure: "A material appears transparent when it does not strongly absorb or diffract light. As far as the absorbance of a solid goes, you pretty much have to take what Nature gives you. Diffraction, however, can be influenced by how the material is prepared.

The boundaries between these regions are called grain boundaries. If the distance between boundaries is smaller than the shortest wavelength of visible light in other words, if the refractive index of the material is uniform with respect to the light passing through it , then the material will appear transparent. Each boundary tends to diffuse the light that passes through; if the regions are small enough, however, the light waves essentially 'jump' right over them. It has no internal grain boundaries, and hence it looks transparent.

Solid silicon dioxide sand , in contrast, has obvious grain boundaries, so it is not transparent. One way to do this is to press a material under force, as is done all the time with potassium bromide, a compound used for infrared spectroscopy in laboratories. Physicists sometimes talk about this in terms of band theory , which says energy levels exist together in regions known as energy bands.

In between these bands are regions, known as band gaps , where energy levels for electrons don't exist at all. Some materials have larger band gaps than others.

Glass is one of those materials, which means its electrons require much more energy before they can skip from one energy band to another and back again. Photons of visible light — light with wavelengths of to nanometers, corresponding to the colors violet, indigo, blue, green, yellow, orange and red — simply don't have enough energy to cause this skipping.

Consequently, photons of visible light travel through glass instead of being absorbed or reflected, making glass transparent. At wavelengths smaller than visible light, photons begin to have enough energy to move glass electrons from one energy band to another. For example, ultraviolet light, which has a wavelength ranging from 10 to nanometers, can't pass through most oxide glasses, such as the glass in a window pane.

This makes a window, including the window in our hypothetical house under construction, as opaque to ultraviolet light as wood is to visible light.

Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Physical Science. Chemical Processes and Tests. What Makes Glass Transparent? That glass window is doing what it does best — keeping the inclement weather out while still permitting light to pass through.

The substance absorbs the photon. This occurs when the photon gives up its energy to an electron located in the material. Armed with this extra energy, the electron is able to move to a higher energy level, while the photon disappears. The substance reflects the photon.

To do this, the photon gives up its energy to the material, but a photon of identical energy is emitted. The substance allows the photon to pass through unchanged. Known as transmission, this happens because the photon doesn't interact with any electron and continues its journey until it interacts with another object.

Transparent Glass FAQ Why is glass transparent to visible light but opaque to ultraviolet and infrared? This is because of the energy UV and infrared light hold and their wavelengths.

This is because different colour light haas different energy levels and so depending on the energy needed to 'move' electrons to a higher energy state some colours will be strong enough and absorbed and others wont and will pass through.

NOTE, I am simplifying a bit, for example it doesn't literally 'pass through' as such, the the way the electron and photon interact are quantum mechanical and none of this includes polarization, reflection etc.

That said on a macro scale, without the quantum detail which would take years to teach this is what is happening. There is no absorption and re-emission process when light travels in a transparent medium. Medium does absorb some portion of the light, but no re-emission happens, or re-emission is so small that it can be neglected. The absorption doesn't make electrons to transit to higher energy levels, but to increase their kinetic random movement, including atom's random vibration.

This results in increased temperature of the glass. Some fluorescent substances absorb visible light and re-emit it. When this happens, after the visible light is turned off, the matter has its own light emitted for a while. This involves electron energy levels transition. This answer is a little circular and like Burley's. Transparent materials have uniform electromagnetic coupling between its molecules. Think of glass as a uniform array of tiny capacitors.

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Active 2 years, 2 months ago. Viewed k times. Improve this question. Add a comment. Active Oldest Votes. There are important differences in these absorption possibilities: Atoms absorb well-defined discrete frequencies.

Usually single atoms absorb only a few frequencies - it depends on the energetic spectrum of its electrons. Regarding atomic absorption, the graph of absorption plotted as a function of frequency of light contains well-defined peaks for frequencies when absorption occurs, and no absorption at all between them. Molecules absorb discrete frequencies but there are many more absorption lines because even a simple molecule has many more energetic levels than any atom.

So molecules absorb much more light. Crystalline lattices may absorb not only discrete frequencies but also continuous bands of frequencies, mainly because of discrepancies in the crystalline structure.

Improve this answer. Do other type of photons behave like visible light i. When You try to analyse light and matter interactions there is many process to take into account. But from the form of the question I presume You need a basic level answer.