Specimens are cut into extremely thin sections, and the transmission electron microscope aims an electron beam through a section, just as a light microscope aims a beam of light through a specimen. However, instead of lenses made of glass, the transmission electron microscope uses electromagnets as...
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or a glass lightbulb. Glass is one of the world's oldest and most versatile human-created materials. Let's find out some more about it.Photo: Glass riddle: How does something transparent to light appear colored? The colors in this glass aren't really there! Glass lenses refract (bend) ...
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In the early days of eyewear, all lenses were made of glass. While glass offered great vision quality, the lenses came with a high risk of shattering. Now there are many choices for lens materials, each with drawbacks and benefits. The most popular options include plastic,polycarbonateand Triv...
Here arethe basic componentsof modern glass: Pure Silica(SiO2 , fused quartz) represents 70-74% weight of modern glass. In ancient times, glassworkers prepared recipes with more than 90% of pure silica, but because this substance has a melting point of about 2000 degrees centigrade (3,600°...
Some glasses wearers turn to DIY solutions, including vinegar and glass-etching compounds that can be purchased at craft stores. Since DIY results may vary, and it's your eyes and vision that are at stake, crazing repair is best left to professionals. Check first to see if your lenses are...
Glasses used to be made of glass. Now, most are made of plastic. Plastic lenses are lighter and can be treated with coatings to protect your eyes. But plastic is more likely to scratch than glass. Other glasses can meet specific needs: ...
根据第二段Early glasses were like magnifying glasses (放大镜).And most of them weren't even made of glass!Instead,many early eyeglasses contained quartz (石英).That's because most glass at that time was not clear,so it wouldn't have worked well for eyeglasses.(早期的眼镜就像放大镜。而且...
;“Sunglasses”;“contact lenses (隐形眼镜), ”以及“fashion glasses”可知文章提到了五种眼镜。故选C。 (5)题详解: 标题归纳题。通读全文,尤其根据“Now glasses have become a daily necessity (必需品) for some of us. So what do you know about them?”可知文章说的是眼镜是如何发展的。故选A...