已知一透镜将物体放大-3倍,透镜向物体移进16mm,物体放大-4倍,求透镜焦距
人气:275 ℃ 时间:2020-06-13 19:17:07
解答
设透镜的焦距为f,因为m=v/u,则根据题意得:
-3=v/u .(1)
-4=v/(u-16).(2)
由(1)得:v=-3u .(3)
将(3)代入(2)并整理得:u=64.(4)
将(4)代入(3)得:v=-192
1/f=1/u+v/1=1/64-1/192=1/96
所以,f=96(mm)
答:略.
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