評論
打印
Don:What a great day for a drive! How do you like my new Ferarri?
唐:多么適合兜風的天氣!你覺得我的新法拉利怎么樣?
Yael:Very fancy.
雅艾爾:非常花俏。
Don:Best of all, the radio works, so we can still enjoy A Moment of Science.
唐:最重要的是,收音機也很酷,所以我們仍然可以享受科學時刻節目。
Hey, I think it's coming on now.
嘿,我想節目馬上就來了。
Yael:Hey, where'd the signal go?
雅艾爾:嘿,信號去哪里了?
Don:It must be because we're driving through a tunnel. Try an FM station.
唐:那一定是因為我們開車穿過一個隧道的緣故。試試一個FM調頻電臺。
Yael:There it is!
雅艾爾:有了!
How come we can hear FM longer in a tunnel than AM?
為什么我們在隧道中能聽到FM調頻而不是AM調幅?
Don:It's because FM stations transmit at higher frequencies.
唐:這是因為FM調頻電臺傳輸更高的頻率。
They generally go from eighty-eight to one-hundred-and-eight megahertz.
通常會從88到108兆赫。
That's over a hundred million cycles per second.
超過每秒一億次。
Yael:Wow! That's pretty fast.
雅艾爾:哇!那可是相當快。
Don:As a result, a single radio wave from an FM station is only a few meters long, about the size of a car.
唐:結果, FM電臺單一的無線電波只有幾米長,約相當于一輛車。
An AM station is putting out radio waves that are hundreds of times as long!
而AM電臺伸展數百倍長的無線電波!
Yael:So the longer wavelengths can't make it as easily into tunnels?
雅艾爾:那長的電波不是更容易進入隧道嗎?
Don:Long wavelengths tend to be absorbed or blocked as they try to enter the smaller tunnel.
唐:長電波在試圖進入較小的隧道時往往被吸收或阻礙。
The higher-energy and shorter-wavelength waves from an FM station aren't absorbed or blocked as much.
而FM電臺的高能量和短波長電波沒有被吸收或阻礙。
Instead, they tend to bounce around and get reflected off of surfaces.
相反,它們被從表面反彈和反射。
Yael:Like the inside of a tunnel.
雅艾爾:像是隧道里。
Don:Yep. Of course, they only bounce so far.
唐:是的。當然,它們只是反彈到這段。
If the tunnel is long enough, even FM stations fade out until you come out the other end.
如果隧道足夠長,甚至直到你從隧道另一端出來FM電臺也會漸漸弱化。
Yael:Here we are!
雅艾爾:我們現在就出來了!
