时差N小时 隧道里没信号怎么办?(下)（在线收听）

They generally go from eighty-eight to one-hundred-and-eight megahertz.

通常会从88到108兆赫。

That's over a hundred million cycles per second.

超过每秒一亿次。

Wow! That's pretty fast.

哇!那可是相当快。

As a result, a single radio wave from an FM station is only a few meters long, about the size of a car.

结果，FM电台单一的无线电波只有几米长,约相当于一辆车。

An AM station is putting out radio waves that are hundreds of times as long!

而AM电台伸展数百倍长的无线电波!

So the longer wavelengths can't make it as easily into tunnels?

那长的电波不是更容易进入隧道吗?

Long wavelengths tend to be absorbed or blocked as they try to enter the smaller tunnel.

长电波在试图进入较小的隧道时往往被吸收或阻碍。

The higher-energy and shorter-wavelength waves from an FM station aren't absorbed or blocked as much.

而FM电台的高能量和短波长电波没有被吸收或阻碍。

Instead, they tend to bounce around and get reflected off of surfaces.

相反,它们被从表面反弹和反射。

Like the inside of a tunnel.

像是隧道里。

Yep. Of course, they only bounce so far.

是的。当然,它们只是反弹到这段。

If the tunnel is long enough, even FM stations fade out until you come out the other end.

如果隧道足够长,甚至直到你从隧道另一端出来FM电台也会渐渐弱化。

Here we are!

我们现在就出来了!