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为什么金属有光泽?

Why Are Metals Shiny?

科学秀
SciShow
金属为啥会发光
QQS: why is metal shiny?
闪亮的东西引人注目
nothing grabs your eye quite like shiny and when it comes to shine,
镜子和首饰的耀眼金属光泽无与伦比
nothing beats good metallic sheen from mirrors to jewelry.
金属如金子 因闪耀能力而珍贵
Medals are prized for their ability to glitter like well gold.
它们的光泽主要是一种内在属性
Their shininess is basically a built inproperty and there’s a good reason
其电子行为的诡异方式有一种合理解释
why it’s a quirk of the weird way their electron behavior.
在金属原子中 最外层电子与原子核连接微弱
In a metal atom the outermost electrons are only weakly attached to the nucleus.
当大量金属原子聚集结合为块状
When a bunch of metal atoms come together in a chunk,
这些外层电子自由移动 就产生了科学家通常所说的电子海
these outer electrons wiggle free creating what scientists usually think
即大量带负电荷的电子游荡在带正电的金属阳离子周围
of as a negatively charged sea of electrons flowing around a network of
positively charged ions.
这种移动的电子海是金属的重要组成部分
This moving sea is a big part of what makes metals metal.
比如 它们可以被捶打成各种形状而不会断裂
For example you can hammer them into different shapes without cracking them
这是因为这些电子可以移动去填补向四周转移的原子核的位置
because the electrons can move to compensate for the atomic nuclei
而那些自由电子有很好的导电性
shifting around and all those free electrons are great at conducting electricity
这也是为什么金属有光泽的原因我们所说的闪光其实是光的反射
that’s also why metals are shiny. What we call shine is actually reflected light
但是它不像网球一样仅仅从表面上弹开
but it doesn’t just bounce off the surface like a tennis ball.
而是当一束光照射到电子海时
Instead when a wave of light hits the sea of electrons the electrons
电子吸收光能 这使得它们轻微的震荡
absorb the light waves energy which makes them wobble a little
这种活动产生了第二次光波 这种光波从金属表面辐射出去
that movement generates a second wave of light, one that radiates back up from the surface
形成我们所看的光泽
that’s what we see is a shine.
自由电子和金属产生的振荡与可见光波长匹配
The free electrons and metals are especially good at this vibrating to match visible light thing
但不同的金属发光方式不同这很大程度上取决于金属本身
but deferent metals shine in different ways. That’s big as dependingon the metal.
电子海具有不同的质量及密度 它们影响着电子自由移动的程度
The sea of electrons will have a different mass and density which affects how freely the electrons can
以及它们的振荡是否能够产生可见光
move and therefore whether they can vibrate to match the incoming wave.
大部分金属是银白色的 是因为它们反射了绝大部分可见光
Most metals are silvery because they reflect most visible light but
这使得它们的颜色 比纯白要更深一些
not all of it which makes them a little darker than pure white. A few metals like gold and
有些金属像金和铜 不能反射蓝光
copper aren’t able to reflect the bluest wavelengths of light so they shine with
因此它们的光泽呈现红或黄
a reddish or yellowish hue
此外金属不一定能反射高能量波如紫外线和X光
and there are no guarantees that a metal will reflect higher energy waves like UV and x-rays at all.
光波穿透到金属里面
Waves are reflected penetrate into the metal
要么被其轻易吸收 要么直接穿透金属这取决于金属种类和厚度
can easily be absorbed or pass on through depending on both the type of metal and how thick it is.
举个栗子 银是可见光最好的反射介质之一这也是为什么
Silver for example is one of the best reflectors of visible light which is why it was one of the
银是最早用作镜子材料的金属之一 但是它在反射紫外线方面极差
first metals used for mirrors but it’s terrible at reflecting UV rays
如果把你关在薄薄的银盒子里面 房子太阳直接曝晒
If i locked you in a thin silver box and put it in direct sunlight it would be
即使盒子里面是全黑 你还是会晒伤
completely dark in there but you could still get sunburned, you know,
而像锡和铝这样的金属能更好的反射紫外线
hypothetically. Metals like tin and aluminum are much better at reflecting
所以它们用于屋顶
ultraviolet light which is why they’re used in roofing.
另外 铅甚至能反射这种能够穿透大多数金属的高能量X光
Lead on the other hand can reflect even the high-energy x-rays that penetrate most metals making it an
在医生不想让你身体的某些部位被X光照射时铅是保护身体器官的理想材料
ideal way to protect parts of your body that your doctor doesn’t want x-ray.
这也是超人都无法透视它的原因 所以金属闪耀各种光泽
That’s also why Superman can’t see through it. So metals can shine in lots of different ways
都源于相同的道理 就是那些电子的运动
but it all comes from the same thing, a bunch of electrons moving around.
感谢提问 尤其感谢赞助商对patreon的支持 patreon一直致力于回答这些提问
Thanks for asking and thanks especially to all of our patronson patreon who keep these answers coming.
如果想上传问题并得到解答就去patreon.com/scishow
If you would like to submit questions to be answered you can go to patreon.com/scishow
#音乐#
#music #

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视频概述

介绍金属闪光的原理

听录译者

收集自网络

翻译译者

小鸭

审核员

LD

视频来源

https://www.youtube.com/watch?v=inrFPEHXzjs

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