问题描述： 为什么凸透镜物距大于2f 相距小于2F大于F 1个回答 分类：数学 2014-11-16 问题解答： 我来补答 根据公式1/f=1/u+1/V可得,1/V=1/f-1/u所以,V=uf/(u-f)因为,u＞2f,所以可以用特殊值法来验证当u=2.5f 时,V=uf/(u-f)=2.5f×f/(2.5f-f)=5f/3当u=3f 时,V=uf/(u-f)=3f×f/(3f-f)=3f/2当u=3.5f 时,V=uf/(u-f)=3.5f×f/(3.5f-f)=7f/5当u=4f 时,V=uf/(u-f)=4f×f/(4f-f)=4f/3.当u=nf 时(n＞2),V=uf/(u-f)=nf×f/(nf-f)=nf/(n-1)因为,n/(n-1)=1+1/(n-1),而当n＞2时,1＜1+1/(n-1)＜2所以,f＜V＜2f 展开全文阅读
