题目内容
如图所示为一简易火灾报警装置,其原理是:竖直放置的试管中装有水银,当温度升高时,水银柱上升,使电路导通,蜂鸣器发出报警的响声。27℃时,被封闭的理想气体气柱长L1为20cm,水银上表面与导线下端的距离L2为5cm。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241551187162200.jpg)
⑴当温度达到多少℃时,报警器会报警?
⑵如果大气压降低,试分析说明该报警器的报警温度会受到怎样的影响?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241551187162200.jpg)
⑴当温度达到多少℃时,报警器会报警?
⑵如果大气压降低,试分析说明该报警器的报警温度会受到怎样的影响?
(2)①
②报警温度降低
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241551187321013.png)
试题分析:①温度升高时,下端气体等压变化:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155118872627.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155118997752.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241551187321013.png)
②由玻马定律,同样温度下,大气压降低则下端气柱变长,即V1变大。而刚好报警时V2不变,由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155118872627.png)
点评:难度中等,应明确气体的体积、温度和压强变化,找到初末位置的参量
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目