题目内容
频率为50 Hz的交变电流,电压为u="100sin(ωt)" V,把它加在激发电压、熄灭电压均为50 V的霓虹灯的两端,求在半个周期内霓虹灯发光的时间.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635285313.gif)
由u=100sinωt可知
u="50" V时sinωt=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635301225.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635332438.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635363474.gif)
在半个周期内霓虹灯的发光时间:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635379556.gif)
由题意可知ω=2πf=100π代入上式:
.
u="50" V时sinωt=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635301225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635316444.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635332438.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635348475.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635363474.gif)
在半个周期内霓虹灯的发光时间:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635379556.gif)
由题意可知ω=2πf=100π代入上式:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635394663.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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