题目内容
正弦交变电压u="50sin314t" V加在一氖管的两端,已知当氖管两端的电压达到
V时才开始发光,则此氖管在一个周期内发光的总时间为……( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728278439.png)
A.0.02 s | B.0.0025 s |
C.0.01 s | D.0.005 s |
C
根据交流电的瞬时表达式画出Ut图象,如下图所示.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241207283414489.jpg)
当瞬时值为U=25
V时,对应于四个时刻(一个周期内),即:25
=50sin314t V,sin314t=
,所以t1=
s、t2=
s、t3=
s、t4=
s,
所以
=0.01s
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241207283414489.jpg)
当瞬时值为U=25
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728372336.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728372336.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728450411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728544416.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728590486.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728637458.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728746462.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120728934936.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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