but something certainly is bringing the program from the station.
What is this silent carrier?
The answer is radio waves. We can not see radio waves or feel
them or even hear them. In fact, nobody knows exactly what they are.
But we do know that they are made by electricity, and we have
learned how to use them.
At the broadcasting station people talk or sing, instruments (乐器)
play, doors slam(砰) ,and all of these make sound waves. The sound
waves reach the microphone, and here they are changed into
electricity. Then from a tall tower called the broadcasting aerial
(天线) ,electricity sends radio waves. The waves travel in every
direction, and some of them reach our radio aerial. Now a wonderful
thing happens. The radio waves start an electricity current (电流) in
our aerial like the one that was first made in the broadcasting
station. Finally, the loudspeaker in our set changes electricity
《单元整体教案NSEFCII-U02(The first period)(第2页)》出自：www.89xue.com网
www.89xue.com into sound, and we hear the program.
The First Period
Teaching Aims:
1. Learn and master the following words and phrases:
media, reliable, fire, face, difficulty, elect, go up, burn down,
injure
2. Practise expressing opinion using the following:
What do you think of…?
What's your opinion?
Why do you choose…?
Perhaps…is more important.
I would rather choose.…
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