in properties of electromagnetic radiation.

多样化性质的表现
Certain forms of electromagnetic radiation are apparent to us

我们能看到某些形式电磁辐射
because our retinas can detect it.

因为我们的视网膜能捕捉到这些辐射
That's the visible part of the spectrum which I've shown here.

即光谱的可见光部分在这张图上
Now, what this shows is the entire electromagnetic spectrum arranged

这里所展示的是全部的电磁光谱
on a scale from very short wavelength up to very long wavelength,

按照波长由短到长排列
and these are in centimeters.

这些是以厘米计算波长的电磁波
The visible part of the spectrum is around a micron or so,

可见光的波长是一微米左右
or slightly less than a micron.

或者略小于一微米
It's around 400 nanometers to 700 nanometers is the visible spectrum.

四百到七百纳米部分是可见光光谱
Now, why is this visible spectrum?

那么为什么这部分光是可见的呢
Because when radiation with this wavelength hits your eye,

因为当这一波长的辐射接触你的眼睛