doufenghui
幼苗
共回答了20个问题采纳率:75% 举报
如图所示,广场上有一个半径R=45m的圆圈,AB是它的一条直径,在圆心O和圆周上的A点分别装有同样的电磁波源,它们发出的球面电磁波长λ=" 10" m.有一人站在B处用接收器恰好收不到信号,他沿圆周向A走,在走到A之前,他有几次收不到信号、有几次收到的信号最强?
九次 , 八次
O到B的距离=R=45米=4.5
![](https://img.yulucn.com/upload/4/c7/4c78ba587b9bf083349f4b1d2ed9f293_thumb.jpg)
,A到B的距离=2R=90米=9
![](https://img.yulucn.com/upload/4/c7/4c78ba587b9bf083349f4b1d2ed9f293_thumb.jpg)
.
当B沿圆周走向A的过程中,A到B的距离会出现下述两组数值:
8.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、7.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、6.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、5.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、4.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、3.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、2.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、1.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、0.5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
;
8
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、7
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、6
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、5
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、4
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、3
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、2
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
、
![](https://img.yulucn.com/upload/b/69/b69732d75cc7a58b3006dadb249cf429_thumb.jpg)
.
第一组数值表示A、O到B的路程差是半波长的奇数倍,信号最弱收不到,共有九次.
第二组数值表示A、O到B的路程差是波长的整数倍,信号最强,共有八次.
1年前
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