Name: 【TED-Ed】為什麼玻璃是透明的？- 馬克-米奧多尼克 (【TED-Ed】Why is glass transparent? - Mark Miodownik)
Uploaded: 2021-01-14T04:56:04.000Z
Duration: 4 min 8 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

You might want to grab a pair of binoculars, too,

how something so solid can be so invisible?

we have to understand what glass actually is,

These react together to form silicon dioxide,

into a regular crystalline form known as quartz.

where it often makes up most of the grains

and is the main ingredient in most type of glass.

Of course, you probably noticed that glass

isn't made of multiple tiny bits of quartz,

For one thing, the edges of the rigidly formed grains

and smaller defects within the crystal structure

reflect and disperse light that hits them.

But when the quartz is heated high enough

the extra energy makes the molecules vibrate

until they break the bonds holding them together

Unlike water, though, liquid silicon dioxide

does not reform into a crystal solid when it cools.

and the result is what is called an amorphous solid.

A solid material with the chaotic structure of a liquid,

which allows the molecules to freely fill in any gaps.

without being scattered in different directions.

rather than being absorbed as with most solids.

You may know that an atom consists of a nucleus

In fact, if an atom were the size of a sports stadium,

the nucleus would be like a single pea in the center,

while the electrons would be like grains of sand

but why aren't all materials transparent?

The answer has to do with the different energy levels

Think of these as different rows of seats

An electron is initially assigned to sit in a certain row,

Otherwise, it will just let the photon pass by,

can't provide enough energy for an electron

Photons from ultraviolet light, on the other hand,

which is why you can't get a suntan through glass.

solid and transparent has given glass many uses