题目内容
如图是示波管的原理图,它由电子枪、偏转电极(XX'和YY')、荧光屏组成,管内抽成真空。给电子枪通电后,如果在偏转电极XX'和YY'上都没有加电压,电子束将打在荧光屏的中心O点,在那里产生一个亮斑。要想让亮斑移到荧光屏的正上方,需在偏转电极__________(选填“XX'”或“YY'”)上加电压,且__________板电势高(选填“X”、“X'”、“Y”或“Y'”)。要想在荧光屏上出现一条沿水平方向展开的正弦曲线,需在偏转电极__________(选填“XX'”或“YY'”)上加扫描电压、在偏转电极__________(选填“XX'”或“YY'”)上加按照正弦规律变化的电压。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500302398417508.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500302398417508.png)
⑵
(每空1分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024015356.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024031310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024046381.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024015356.png)
试题分析:在偏转电极XX'和YY'上都没有加电压,电子束将打在荧光屏的中心O点,要想让亮斑移到荧光屏的正上方,即让粒子在竖直方向上即
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024078356.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024078356.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024031310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024031310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024156382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003024078356.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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